[LTP] [PATCH] pac_common: redesign function for finding Start Of Frame

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* [LTP] [PATCH] pac_common: redesign function for finding Start Of Frame
@ 2009-10-04 20:55 ` Németh Márton
  0 siblings, 0 replies; 8+ messages in thread
From: Németh Márton @ 2009-10-04 20:55 UTC (permalink / raw)
  To: Jean-Francois Moine, Thomas Kaiser, Kyle Guinn, Theodore Kilgore
  Cc: ltp-list, LKML, V4L Mailing List

From: Márton Németh <nm127@freemail.hu>

The original implementation of pac_find_sof() does not always find
the Start Of Frame (SOF) marker. Replace it with a state machine
based design.

The change was tested with Labtec Webcam 2200.

Signed-off-by: Márton Németh <nm127@freemail.hu>
---
--- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
+++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
@@ -33,6 +33,45 @@
 static const unsigned char pac_sof_marker[5] =
 		{ 0xff, 0xff, 0x00, 0xff, 0x96 };

+/*
+   The following state machine finds the SOF marker sequence
+   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
+
+	   +----------+
+	   | 0: START |<---------------\
+	   +----------+<-\             |
+	     |       \---/otherwise    |
+	     v 0xff                    |
+	   +----------+ otherwise      |
+	   |     1    |--------------->*
+	   |          |                ^
+	   +----------+                |
+	     |                         |
+	     v 0xff                    |
+	   +----------+<-\0xff         |
+	/->|          |--/             |
+	|  |     2    |--------------->*
+	|  |          | otherwise      ^
+	|  +----------+                |
+	|    |                         |
+	|    v 0x00                    |
+	|  +----------+                |
+	|  |     3    |                |
+	|  |          |--------------->*
+	|  +----------+ otherwise      ^
+	|    |                         |
+   0xff |    v 0xff                    |
+	|  +----------+                |
+	\--|     4    |                |
+	   |          |----------------/
+	   +----------+ otherwise
+	     |
+	     v 0x96
+	   +----------+
+	   |  FOUND   |
+	   +----------+
+*/
+
 static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
 					unsigned char *m, int len)
 {
@@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc

 	/* Search for the SOF marker (fixed part) in the header */
 	for (i = 0; i < len; i++) {
-		if (m[i] == pac_sof_marker[sd->sof_read]) {
-			sd->sof_read++;
-			if (sd->sof_read == sizeof(pac_sof_marker)) {
+		switch (sd->sof_read) {
+		case 0:
+			if (m[i] == 0xff)
+				sd->sof_read = 1;
+			break;
+		case 1:
+			if (m[i] == 0xff)
+				sd->sof_read = 2;
+			else
+				sd->sof_read = 0;
+			break;
+		case 2:
+			switch (m[i]) {
+			case 0x00:
+				sd->sof_read = 3;
+				break;
+			case 0xff:
+				/* stay in this state */
+				break;
+			default:
+				sd->sof_read = 0;
+			}
+			break;
+		case 3:
+			if (m[i] == 0xff)
+				sd->sof_read = 4;
+			else
+				sd->sof_read = 0;
+			break;
+		case 4:
+			switch (m[i]) {
+			case 0x96:
+				/* Pattern found */
 				PDEBUG(D_FRAM,
 					"SOF found, bytes to analyze: %u."
 					" Frame starts at byte #%u",
 					len, i + 1);
 				sd->sof_read = 0;
 				return m + i + 1;
+				break;
+			case 0xff:
+				sd->sof_read = 2;
+				break;
+			default:
+				sd->sof_read = 0;
 			}
-		} else {
+			break;
+		default:
 			sd->sof_read = 0;
 		}
 	}

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^ permalink raw reply	[flat|nested] 8+ messages in thread

* [PATCH] pac_common: redesign function for finding Start Of Frame
@ 2009-10-04 20:55 ` Németh Márton
  0 siblings, 0 replies; 8+ messages in thread
From: Németh Márton @ 2009-10-04 20:55 UTC (permalink / raw)
  To: Jean-Francois Moine, Thomas Kaiser, Kyle Guinn, Theodore Kilgore
  Cc: V4L Mailing List, LKML, ltp-list

From: Márton Németh <nm127@freemail.hu>

The original implementation of pac_find_sof() does not always find
the Start Of Frame (SOF) marker. Replace it with a state machine
based design.

The change was tested with Labtec Webcam 2200.

Signed-off-by: Márton Németh <nm127@freemail.hu>
---
--- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
+++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
@@ -33,6 +33,45 @@
 static const unsigned char pac_sof_marker[5] =
 		{ 0xff, 0xff, 0x00, 0xff, 0x96 };

+/*
+   The following state machine finds the SOF marker sequence
+   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
+
+	   +----------+
+	   | 0: START |<---------------\
+	   +----------+<-\             |
+	     |       \---/otherwise    |
+	     v 0xff                    |
+	   +----------+ otherwise      |
+	   |     1    |--------------->*
+	   |          |                ^
+	   +----------+                |
+	     |                         |
+	     v 0xff                    |
+	   +----------+<-\0xff         |
+	/->|          |--/             |
+	|  |     2    |--------------->*
+	|  |          | otherwise      ^
+	|  +----------+                |
+	|    |                         |
+	|    v 0x00                    |
+	|  +----------+                |
+	|  |     3    |                |
+	|  |          |--------------->*
+	|  +----------+ otherwise      ^
+	|    |                         |
+   0xff |    v 0xff                    |
+	|  +----------+                |
+	\--|     4    |                |
+	   |          |----------------/
+	   +----------+ otherwise
+	     |
+	     v 0x96
+	   +----------+
+	   |  FOUND   |
+	   +----------+
+*/
+
 static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
 					unsigned char *m, int len)
 {
@@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc

 	/* Search for the SOF marker (fixed part) in the header */
 	for (i = 0; i < len; i++) {
-		if (m[i] == pac_sof_marker[sd->sof_read]) {
-			sd->sof_read++;
-			if (sd->sof_read == sizeof(pac_sof_marker)) {
+		switch (sd->sof_read) {
+		case 0:
+			if (m[i] == 0xff)
+				sd->sof_read = 1;
+			break;
+		case 1:
+			if (m[i] == 0xff)
+				sd->sof_read = 2;
+			else
+				sd->sof_read = 0;
+			break;
+		case 2:
+			switch (m[i]) {
+			case 0x00:
+				sd->sof_read = 3;
+				break;
+			case 0xff:
+				/* stay in this state */
+				break;
+			default:
+				sd->sof_read = 0;
+			}
+			break;
+		case 3:
+			if (m[i] == 0xff)
+				sd->sof_read = 4;
+			else
+				sd->sof_read = 0;
+			break;
+		case 4:
+			switch (m[i]) {
+			case 0x96:
+				/* Pattern found */
 				PDEBUG(D_FRAM,
 					"SOF found, bytes to analyze: %u."
 					" Frame starts at byte #%u",
 					len, i + 1);
 				sd->sof_read = 0;
 				return m + i + 1;
+				break;
+			case 0xff:
+				sd->sof_read = 2;
+				break;
+			default:
+				sd->sof_read = 0;
 			}
-		} else {
+			break;
+		default:
 			sd->sof_read = 0;
 		}
 	}

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [LTP] [PATCH] pac_common: redesign function for finding Start Of Frame
  2009-10-04 20:55 ` Németh Márton
@ 2009-10-04 20:56   ` Németh Márton
  -1 siblings, 0 replies; 8+ messages in thread
From: Németh Márton @ 2009-10-04 20:56 UTC (permalink / raw)
  To: Jean-Francois Moine, Thomas Kaiser, Kyle Guinn, Theodore Kilgore,
	ltp-list
  Cc: LKML, V4L Mailing List

[-- Attachment #1: Type: text/plain, Size: 4927 bytes --]

Hi,

I wrote a simple test for pac_find_sof(). I implemented a user-space test
which takes the implementation from the source file and calls it directly.
You can find the source code of the test attached.

The test results for the pac_find_sof() implementation in the Linux kernel
2.6.32-rc1 is the following:

Test case 1: exact match
PDEBUG: SOF found, bytes to analyze: 5. Frame starts at byte #5
PASSED

Test case 2: offset 1
PDEBUG: SOF found, bytes to analyze: 6. Frame starts at byte #6
PASSED

Test case 3: offset 1, first byte may be misleading
FAILED

Test case 4: offset 2, first two bytes may be misleading
PDEBUG: SOF found, bytes to analyze: 7. Frame starts at byte #7
PASSED

Test case 5: offset 3, first three bytes may be misleading
FAILED

Test case 6: offset 4, first four bytes may be misleading
FAILED

Test case 7: pattern starts at end of packet and continues in the next one
PDEBUG: SOF found, bytes to analyze: 1. Frame starts at byte #1
PASSED

Test case 8: splited pattern, with misleading first byte
FAILED

Test case 9: splited pattern, with misleading first three bytes
FAILED

Test case 10: no match, extra byte at offset 1
PASSED

Test case 11: no match, extra byte at offset 2
PASSED

Test case 12: no match, extra byte at offset 3
PASSED

Test case 13: no match, extra byte at offset 4
PASSED

I also executed the test with the patched pac_find_sof() implementation
and that one passes all these test cases.

Regards,

	Márton Németh

Németh Márton wrote:
> From: Márton Németh <nm127@freemail.hu>
> 
> The original implementation of pac_find_sof() does not always find
> the Start Of Frame (SOF) marker. Replace it with a state machine
> based design.
> 
> The change was tested with Labtec Webcam 2200.
> 
> Signed-off-by: Márton Németh <nm127@freemail.hu>
> ---
> --- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
> +++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
> @@ -33,6 +33,45 @@
>  static const unsigned char pac_sof_marker[5] =
>  		{ 0xff, 0xff, 0x00, 0xff, 0x96 };
> 
> +/*
> +   The following state machine finds the SOF marker sequence
> +   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
> +
> +	   +----------+
> +	   | 0: START |<---------------\
> +	   +----------+<-\             |
> +	     |       \---/otherwise    |
> +	     v 0xff                    |
> +	   +----------+ otherwise      |
> +	   |     1    |--------------->*
> +	   |          |                ^
> +	   +----------+                |
> +	     |                         |
> +	     v 0xff                    |
> +	   +----------+<-\0xff         |
> +	/->|          |--/             |
> +	|  |     2    |--------------->*
> +	|  |          | otherwise      ^
> +	|  +----------+                |
> +	|    |                         |
> +	|    v 0x00                    |
> +	|  +----------+                |
> +	|  |     3    |                |
> +	|  |          |--------------->*
> +	|  +----------+ otherwise      ^
> +	|    |                         |
> +   0xff |    v 0xff                    |
> +	|  +----------+                |
> +	\--|     4    |                |
> +	   |          |----------------/
> +	   +----------+ otherwise
> +	     |
> +	     v 0x96
> +	   +----------+
> +	   |  FOUND   |
> +	   +----------+
> +*/
> +
>  static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
>  					unsigned char *m, int len)
>  {
> @@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc
> 
>  	/* Search for the SOF marker (fixed part) in the header */
>  	for (i = 0; i < len; i++) {
> -		if (m[i] == pac_sof_marker[sd->sof_read]) {
> -			sd->sof_read++;
> -			if (sd->sof_read == sizeof(pac_sof_marker)) {
> +		switch (sd->sof_read) {
> +		case 0:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 1;
> +			break;
> +		case 1:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 2;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 2:
> +			switch (m[i]) {
> +			case 0x00:
> +				sd->sof_read = 3;
> +				break;
> +			case 0xff:
> +				/* stay in this state */
> +				break;
> +			default:
> +				sd->sof_read = 0;
> +			}
> +			break;
> +		case 3:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 4;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 4:
> +			switch (m[i]) {
> +			case 0x96:
> +				/* Pattern found */
>  				PDEBUG(D_FRAM,
>  					"SOF found, bytes to analyze: %u."
>  					" Frame starts at byte #%u",
>  					len, i + 1);
>  				sd->sof_read = 0;
>  				return m + i + 1;
> +				break;
> +			case 0xff:
> +				sd->sof_read = 2;
> +				break;
> +			default:
> +				sd->sof_read = 0;
>  			}
> -		} else {
> +			break;
> +		default:
>  			sd->sof_read = 0;
>  		}
>  	}
> 


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: test_pac_find_sof.c --]
[-- Type: text/x-csrc; name="test_pac_find_sof.c", Size: 6820 bytes --]


/*
  Test the function pac_find_sof() from file
  linux/drivers/media/video/gspca/pac_common.h

  Test based on Linux kernel 2.6.32-rc1
  Written by Márton Németh <nm127@freemail.hu>, 4 Oct 2009
  Released under GPL
*/

#include <stdio.h>

struct sd {
	unsigned int sof_read;
};

struct gspca_dev {
    struct sd* sd;
};

#define PDEBUG(level, fmt, args...) \
	do {\
		printf("PDEBUG: " fmt "\n", ## args); \
	} while (0)

#include "pac_common.h"

int tc1() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 1: exact match\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[5]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc2() {
	static unsigned char test[] = { 0x00, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 2: offset 1\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[6]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc3() {
	static unsigned char test[] = { 0xff, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 3: offset 1, first byte may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[6]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc4() {
	static unsigned char test[] = { 0xff, 0x00, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 4: offset 2, first two bytes may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[7]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc5() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 5: offset 3, first three bytes may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[8]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc6() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 6: offset 4, first four bytes may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[9]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc7() {
	static unsigned char test1[] = { 0xff, 0xff, 0x00, 0xff };
	static unsigned char test2[] = { 0x96 };
	unsigned char* p1;
	unsigned char* p2;
	struct sd sd;
	int result = 0;

	printf("Test case 7: pattern starts at end of packet and continues in the next one\n");
	sd.sof_read = 0;
	p1 = pac_find_sof((struct gspca_dev*)&sd, test1, sizeof(test1));
	p2 = pac_find_sof((struct gspca_dev*)&sd, test2, sizeof(test2));
	if (p1 == NULL && p2 == &test2[1]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc8() {
	static unsigned char test1[] = { 0xff, 0xff, 0xff, 0x00, 0xff };
	static unsigned char test2[] = { 0x96 };
	unsigned char* p1;
	unsigned char* p2;
	struct sd sd;
	int result = 0;

	printf("Test case 8: splited pattern, with misleading first byte\n");
	sd.sof_read = 0;
	p1 = pac_find_sof((struct gspca_dev*)&sd, test1, sizeof(test1));
	p2 = pac_find_sof((struct gspca_dev*)&sd, test2, sizeof(test2));
	if (p1 == NULL && p2 == &test2[1]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc9() {
	static unsigned char test1[] = { 0xff, 0xff, 0x00, 0xff, 0xff, 0x00, 0xff };
	static unsigned char test2[] = { 0x96 };
	unsigned char* p1;
	unsigned char* p2;
	struct sd sd;
	int result = 0;

	printf("Test case 9: splited pattern, with misleading first three bytes\n");
	sd.sof_read = 0;
	p1 = pac_find_sof((struct gspca_dev*)&sd, test1, sizeof(test1));
	p2 = pac_find_sof((struct gspca_dev*)&sd, test2, sizeof(test2));
	if (p1 == NULL && p2 == &test2[1]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc10() {
	static unsigned char test[] = { 0xff, 0xaa, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 10: no match, extra byte at offset 1\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc11() {
	static unsigned char test[] = { 0xff, 0xff, 0xaa, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 11: no match, extra byte at offset 2\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc12() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xaa, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 12: no match, extra byte at offset 3\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc13() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0xaa, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 13: no match, extra byte at offset 4\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}


int main() {
	int result = 0;

	result += tc1();
	result += tc2();
	result += tc3();
	result += tc4();
	result += tc5();
	result += tc6();
	result += tc7();
	result += tc8();
	result += tc9();
	result += tc10();
	result += tc11();
	result += tc12();
	result += tc13();

	return result;
}

[-- Attachment #3: Type: text/plain, Size: 401 bytes --]

------------------------------------------------------------------------------
Come build with us! The BlackBerry&reg; Developer Conference in SF, CA
is the only developer event you need to attend this year. Jumpstart your
developing skills, take BlackBerry mobile applications to market and stay 
ahead of the curve. Join us from November 9&#45;12, 2009. Register now&#33;
http://p.sf.net/sfu/devconf

[-- Attachment #4: Type: text/plain, Size: 155 bytes --]

_______________________________________________
Ltp-list mailing list
Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] pac_common: redesign function for finding Start Of Frame
@ 2009-10-04 20:56   ` Németh Márton
  0 siblings, 0 replies; 8+ messages in thread
From: Németh Márton @ 2009-10-04 20:56 UTC (permalink / raw)
  To: Jean-Francois Moine, Thomas Kaiser, Kyle Guinn, Theodore Kilgore,
	ltp-list
  Cc: V4L Mailing List, LKML

[-- Attachment #1: Type: text/plain, Size: 4748 bytes --]

Hi,

I wrote a simple test for pac_find_sof(). I implemented a user-space test
which takes the implementation from the source file and calls it directly.
You can find the source code of the test attached.

The test results for the pac_find_sof() implementation in the Linux kernel
2.6.32-rc1 is the following:

Test case 1: exact match
PDEBUG: SOF found, bytes to analyze: 5. Frame starts at byte #5
PASSED

Test case 2: offset 1
PDEBUG: SOF found, bytes to analyze: 6. Frame starts at byte #6
PASSED

Test case 3: offset 1, first byte may be misleading
FAILED

Test case 4: offset 2, first two bytes may be misleading
PDEBUG: SOF found, bytes to analyze: 7. Frame starts at byte #7
PASSED

Test case 5: offset 3, first three bytes may be misleading
FAILED

Test case 6: offset 4, first four bytes may be misleading
FAILED

Test case 7: pattern starts at end of packet and continues in the next one
PDEBUG: SOF found, bytes to analyze: 1. Frame starts at byte #1
PASSED

Test case 8: splited pattern, with misleading first byte
FAILED

Test case 9: splited pattern, with misleading first three bytes
FAILED

Test case 10: no match, extra byte at offset 1
PASSED

Test case 11: no match, extra byte at offset 2
PASSED

Test case 12: no match, extra byte at offset 3
PASSED

Test case 13: no match, extra byte at offset 4
PASSED

I also executed the test with the patched pac_find_sof() implementation
and that one passes all these test cases.

Regards,

	Márton Németh

Németh Márton wrote:
> From: Márton Németh <nm127@freemail.hu>
> 
> The original implementation of pac_find_sof() does not always find
> the Start Of Frame (SOF) marker. Replace it with a state machine
> based design.
> 
> The change was tested with Labtec Webcam 2200.
> 
> Signed-off-by: Márton Németh <nm127@freemail.hu>
> ---
> --- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
> +++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
> @@ -33,6 +33,45 @@
>  static const unsigned char pac_sof_marker[5] =
>  		{ 0xff, 0xff, 0x00, 0xff, 0x96 };
> 
> +/*
> +   The following state machine finds the SOF marker sequence
> +   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
> +
> +	   +----------+
> +	   | 0: START |<---------------\
> +	   +----------+<-\             |
> +	     |       \---/otherwise    |
> +	     v 0xff                    |
> +	   +----------+ otherwise      |
> +	   |     1    |--------------->*
> +	   |          |                ^
> +	   +----------+                |
> +	     |                         |
> +	     v 0xff                    |
> +	   +----------+<-\0xff         |
> +	/->|          |--/             |
> +	|  |     2    |--------------->*
> +	|  |          | otherwise      ^
> +	|  +----------+                |
> +	|    |                         |
> +	|    v 0x00                    |
> +	|  +----------+                |
> +	|  |     3    |                |
> +	|  |          |--------------->*
> +	|  +----------+ otherwise      ^
> +	|    |                         |
> +   0xff |    v 0xff                    |
> +	|  +----------+                |
> +	\--|     4    |                |
> +	   |          |----------------/
> +	   +----------+ otherwise
> +	     |
> +	     v 0x96
> +	   +----------+
> +	   |  FOUND   |
> +	   +----------+
> +*/
> +
>  static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
>  					unsigned char *m, int len)
>  {
> @@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc
> 
>  	/* Search for the SOF marker (fixed part) in the header */
>  	for (i = 0; i < len; i++) {
> -		if (m[i] == pac_sof_marker[sd->sof_read]) {
> -			sd->sof_read++;
> -			if (sd->sof_read == sizeof(pac_sof_marker)) {
> +		switch (sd->sof_read) {
> +		case 0:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 1;
> +			break;
> +		case 1:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 2;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 2:
> +			switch (m[i]) {
> +			case 0x00:
> +				sd->sof_read = 3;
> +				break;
> +			case 0xff:
> +				/* stay in this state */
> +				break;
> +			default:
> +				sd->sof_read = 0;
> +			}
> +			break;
> +		case 3:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 4;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 4:
> +			switch (m[i]) {
> +			case 0x96:
> +				/* Pattern found */
>  				PDEBUG(D_FRAM,
>  					"SOF found, bytes to analyze: %u."
>  					" Frame starts at byte #%u",
>  					len, i + 1);
>  				sd->sof_read = 0;
>  				return m + i + 1;
> +				break;
> +			case 0xff:
> +				sd->sof_read = 2;
> +				break;
> +			default:
> +				sd->sof_read = 0;
>  			}
> -		} else {
> +			break;
> +		default:
>  			sd->sof_read = 0;
>  		}
>  	}
> 


[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #2: test_pac_find_sof.c --]
[-- Type: text/x-csrc; name="test_pac_find_sof.c", Size: 6504 bytes --]


/*
  Test the function pac_find_sof() from file
  linux/drivers/media/video/gspca/pac_common.h

  Test based on Linux kernel 2.6.32-rc1
  Written by Márton Németh <nm127@freemail.hu>, 4 Oct 2009
  Released under GPL
*/

#include <stdio.h>

struct sd {
	unsigned int sof_read;
};

struct gspca_dev {
    struct sd* sd;
};

#define PDEBUG(level, fmt, args...) \
	do {\
		printf("PDEBUG: " fmt "\n", ## args); \
	} while (0)

#include "pac_common.h"

int tc1() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 1: exact match\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[5]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc2() {
	static unsigned char test[] = { 0x00, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 2: offset 1\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[6]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc3() {
	static unsigned char test[] = { 0xff, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 3: offset 1, first byte may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[6]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc4() {
	static unsigned char test[] = { 0xff, 0x00, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 4: offset 2, first two bytes may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[7]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc5() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 5: offset 3, first three bytes may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[8]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc6() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 6: offset 4, first four bytes may be misleading\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == &test[9]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc7() {
	static unsigned char test1[] = { 0xff, 0xff, 0x00, 0xff };
	static unsigned char test2[] = { 0x96 };
	unsigned char* p1;
	unsigned char* p2;
	struct sd sd;
	int result = 0;

	printf("Test case 7: pattern starts at end of packet and continues in the next one\n");
	sd.sof_read = 0;
	p1 = pac_find_sof((struct gspca_dev*)&sd, test1, sizeof(test1));
	p2 = pac_find_sof((struct gspca_dev*)&sd, test2, sizeof(test2));
	if (p1 == NULL && p2 == &test2[1]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc8() {
	static unsigned char test1[] = { 0xff, 0xff, 0xff, 0x00, 0xff };
	static unsigned char test2[] = { 0x96 };
	unsigned char* p1;
	unsigned char* p2;
	struct sd sd;
	int result = 0;

	printf("Test case 8: splited pattern, with misleading first byte\n");
	sd.sof_read = 0;
	p1 = pac_find_sof((struct gspca_dev*)&sd, test1, sizeof(test1));
	p2 = pac_find_sof((struct gspca_dev*)&sd, test2, sizeof(test2));
	if (p1 == NULL && p2 == &test2[1]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc9() {
	static unsigned char test1[] = { 0xff, 0xff, 0x00, 0xff, 0xff, 0x00, 0xff };
	static unsigned char test2[] = { 0x96 };
	unsigned char* p1;
	unsigned char* p2;
	struct sd sd;
	int result = 0;

	printf("Test case 9: splited pattern, with misleading first three bytes\n");
	sd.sof_read = 0;
	p1 = pac_find_sof((struct gspca_dev*)&sd, test1, sizeof(test1));
	p2 = pac_find_sof((struct gspca_dev*)&sd, test2, sizeof(test2));
	if (p1 == NULL && p2 == &test2[1]) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc10() {
	static unsigned char test[] = { 0xff, 0xaa, 0xff, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 10: no match, extra byte at offset 1\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc11() {
	static unsigned char test[] = { 0xff, 0xff, 0xaa, 0x00, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 11: no match, extra byte at offset 2\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc12() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xaa, 0xff, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 12: no match, extra byte at offset 3\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}

int tc13() {
	static unsigned char test[] = { 0xff, 0xff, 0x00, 0xff, 0xaa, 0x96 };
	unsigned char* p;
	struct sd sd;
	int result = 0;

	printf("Test case 13: no match, extra byte at offset 4\n");
	sd.sof_read = 0;
	p = pac_find_sof((struct gspca_dev*)&sd, test, sizeof(test));
	if (p == NULL) {
		printf("PASSED\n");
	} else {
		printf("FAILED\n");
		result = 1;
	}
	printf("\n");

	return result;
}


int main() {
	int result = 0;

	result += tc1();
	result += tc2();
	result += tc3();
	result += tc4();
	result += tc5();
	result += tc6();
	result += tc7();
	result += tc8();
	result += tc9();
	result += tc10();
	result += tc11();
	result += tc12();
	result += tc13();

	return result;
}

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [LTP] [PATCH] pac_common: redesign function for finding Start Of Frame
  2009-10-04 20:56   ` Németh Márton
@ 2009-10-13 14:43     ` Subrata Modak
  -1 siblings, 0 replies; 8+ messages in thread
From: Subrata Modak @ 2009-10-13 14:43 UTC (permalink / raw)
  To: Németh Márton
  Cc: Jean-Francois Moine, ltp-list, LKML, Theodore Kilgore,
	Thomas Kaiser, V4L Mailing List, Kyle Guinn

On Sun, 2009-10-04 at 22:56 +0200, Németh Márton wrote: 
> Hi,
> 
> I wrote a simple test for pac_find_sof(). I implemented a user-space test
> which takes the implementation from the source file and calls it directly.
> You can find the source code of the test attached.

Németh,

Can you please add this test to LTP then ?

Regards--
Subrata

> 
> The test results for the pac_find_sof() implementation in the Linux kernel
> 2.6.32-rc1 is the following:
> 
> Test case 1: exact match
> PDEBUG: SOF found, bytes to analyze: 5. Frame starts at byte #5
> PASSED
> 
> Test case 2: offset 1
> PDEBUG: SOF found, bytes to analyze: 6. Frame starts at byte #6
> PASSED
> 
> Test case 3: offset 1, first byte may be misleading
> FAILED
> 
> Test case 4: offset 2, first two bytes may be misleading
> PDEBUG: SOF found, bytes to analyze: 7. Frame starts at byte #7
> PASSED
> 
> Test case 5: offset 3, first three bytes may be misleading
> FAILED
> 
> Test case 6: offset 4, first four bytes may be misleading
> FAILED
> 
> Test case 7: pattern starts at end of packet and continues in the next one
> PDEBUG: SOF found, bytes to analyze: 1. Frame starts at byte #1
> PASSED
> 
> Test case 8: splited pattern, with misleading first byte
> FAILED
> 
> Test case 9: splited pattern, with misleading first three bytes
> FAILED
> 
> Test case 10: no match, extra byte at offset 1
> PASSED
> 
> Test case 11: no match, extra byte at offset 2
> PASSED
> 
> Test case 12: no match, extra byte at offset 3
> PASSED
> 
> Test case 13: no match, extra byte at offset 4
> PASSED
> 
> I also executed the test with the patched pac_find_sof() implementation
> and that one passes all these test cases.
> 
> Regards,
> 
> 	Márton Németh
> 
> Németh Márton wrote:
> > From: Márton Németh <nm127@freemail.hu>
> > 
> > The original implementation of pac_find_sof() does not always find
> > the Start Of Frame (SOF) marker. Replace it with a state machine
> > based design.
> > 
> > The change was tested with Labtec Webcam 2200.
> > 
> > Signed-off-by: Márton Németh <nm127@freemail.hu>
> > ---
> > --- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
> > +++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
> > @@ -33,6 +33,45 @@
> >  static const unsigned char pac_sof_marker[5] =
> >  		{ 0xff, 0xff, 0x00, 0xff, 0x96 };
> > 
> > +/*
> > +   The following state machine finds the SOF marker sequence
> > +   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
> > +
> > +	   +----------+
> > +	   | 0: START |<---------------\
> > +	   +----------+<-\             |
> > +	     |       \---/otherwise    |
> > +	     v 0xff                    |
> > +	   +----------+ otherwise      |
> > +	   |     1    |--------------->*
> > +	   |          |                ^
> > +	   +----------+                |
> > +	     |                         |
> > +	     v 0xff                    |
> > +	   +----------+<-\0xff         |
> > +	/->|          |--/             |
> > +	|  |     2    |--------------->*
> > +	|  |          | otherwise      ^
> > +	|  +----------+                |
> > +	|    |                         |
> > +	|    v 0x00                    |
> > +	|  +----------+                |
> > +	|  |     3    |                |
> > +	|  |          |--------------->*
> > +	|  +----------+ otherwise      ^
> > +	|    |                         |
> > +   0xff |    v 0xff                    |
> > +	|  +----------+                |
> > +	\--|     4    |                |
> > +	   |          |----------------/
> > +	   +----------+ otherwise
> > +	     |
> > +	     v 0x96
> > +	   +----------+
> > +	   |  FOUND   |
> > +	   +----------+
> > +*/
> > +
> >  static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
> >  					unsigned char *m, int len)
> >  {
> > @@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc
> > 
> >  	/* Search for the SOF marker (fixed part) in the header */
> >  	for (i = 0; i < len; i++) {
> > -		if (m[i] == pac_sof_marker[sd->sof_read]) {
> > -			sd->sof_read++;
> > -			if (sd->sof_read == sizeof(pac_sof_marker)) {
> > +		switch (sd->sof_read) {
> > +		case 0:
> > +			if (m[i] == 0xff)
> > +				sd->sof_read = 1;
> > +			break;
> > +		case 1:
> > +			if (m[i] == 0xff)
> > +				sd->sof_read = 2;
> > +			else
> > +				sd->sof_read = 0;
> > +			break;
> > +		case 2:
> > +			switch (m[i]) {
> > +			case 0x00:
> > +				sd->sof_read = 3;
> > +				break;
> > +			case 0xff:
> > +				/* stay in this state */
> > +				break;
> > +			default:
> > +				sd->sof_read = 0;
> > +			}
> > +			break;
> > +		case 3:
> > +			if (m[i] == 0xff)
> > +				sd->sof_read = 4;
> > +			else
> > +				sd->sof_read = 0;
> > +			break;
> > +		case 4:
> > +			switch (m[i]) {
> > +			case 0x96:
> > +				/* Pattern found */
> >  				PDEBUG(D_FRAM,
> >  					"SOF found, bytes to analyze: %u."
> >  					" Frame starts at byte #%u",
> >  					len, i + 1);
> >  				sd->sof_read = 0;
> >  				return m + i + 1;
> > +				break;
> > +			case 0xff:
> > +				sd->sof_read = 2;
> > +				break;
> > +			default:
> > +				sd->sof_read = 0;
> >  			}
> > -		} else {
> > +			break;
> > +		default:
> >  			sd->sof_read = 0;
> >  		}
> >  	}
> > 
> 
> ------------------------------------------------------------------------------
> Come build with us! The BlackBerry&reg; Developer Conference in SF, CA
> is the only developer event you need to attend this year. Jumpstart your
> developing skills, take BlackBerry mobile applications to market and stay 
> ahead of the curve. Join us from November 9&#45;12, 2009. Register now&#33;
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> _______________________________________________ Ltp-list mailing list Ltp-list@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/ltp-list


------------------------------------------------------------------------------
Come build with us! The BlackBerry(R) Developer Conference in SF, CA
is the only developer event you need to attend this year. Jumpstart your
developing skills, take BlackBerry mobile applications to market and stay 
ahead of the curve. Join us from November 9 - 12, 2009. Register now!
http://p.sf.net/sfu/devconference
_______________________________________________
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^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [LTP] [PATCH] pac_common: redesign function for finding Start Of Frame
@ 2009-10-13 14:43     ` Subrata Modak
  0 siblings, 0 replies; 8+ messages in thread
From: Subrata Modak @ 2009-10-13 14:43 UTC (permalink / raw)
  To: Németh Márton
  Cc: Jean-Francois Moine, Thomas Kaiser, Kyle Guinn, Theodore Kilgore,
	ltp-list, LKML, V4L Mailing List

On Sun, 2009-10-04 at 22:56 +0200, Németh Márton wrote: 
> Hi,
> 
> I wrote a simple test for pac_find_sof(). I implemented a user-space test
> which takes the implementation from the source file and calls it directly.
> You can find the source code of the test attached.

Németh,

Can you please add this test to LTP then ?

Regards--
Subrata

> 
> The test results for the pac_find_sof() implementation in the Linux kernel
> 2.6.32-rc1 is the following:
> 
> Test case 1: exact match
> PDEBUG: SOF found, bytes to analyze: 5. Frame starts at byte #5
> PASSED
> 
> Test case 2: offset 1
> PDEBUG: SOF found, bytes to analyze: 6. Frame starts at byte #6
> PASSED
> 
> Test case 3: offset 1, first byte may be misleading
> FAILED
> 
> Test case 4: offset 2, first two bytes may be misleading
> PDEBUG: SOF found, bytes to analyze: 7. Frame starts at byte #7
> PASSED
> 
> Test case 5: offset 3, first three bytes may be misleading
> FAILED
> 
> Test case 6: offset 4, first four bytes may be misleading
> FAILED
> 
> Test case 7: pattern starts at end of packet and continues in the next one
> PDEBUG: SOF found, bytes to analyze: 1. Frame starts at byte #1
> PASSED
> 
> Test case 8: splited pattern, with misleading first byte
> FAILED
> 
> Test case 9: splited pattern, with misleading first three bytes
> FAILED
> 
> Test case 10: no match, extra byte at offset 1
> PASSED
> 
> Test case 11: no match, extra byte at offset 2
> PASSED
> 
> Test case 12: no match, extra byte at offset 3
> PASSED
> 
> Test case 13: no match, extra byte at offset 4
> PASSED
> 
> I also executed the test with the patched pac_find_sof() implementation
> and that one passes all these test cases.
> 
> Regards,
> 
> 	Márton Németh
> 
> Németh Márton wrote:
> > From: Márton Németh <nm127@freemail.hu>
> > 
> > The original implementation of pac_find_sof() does not always find
> > the Start Of Frame (SOF) marker. Replace it with a state machine
> > based design.
> > 
> > The change was tested with Labtec Webcam 2200.
> > 
> > Signed-off-by: Márton Németh <nm127@freemail.hu>
> > ---
> > --- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
> > +++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
> > @@ -33,6 +33,45 @@
> >  static const unsigned char pac_sof_marker[5] =
> >  		{ 0xff, 0xff, 0x00, 0xff, 0x96 };
> > 
> > +/*
> > +   The following state machine finds the SOF marker sequence
> > +   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
> > +
> > +	   +----------+
> > +	   | 0: START |<---------------\
> > +	   +----------+<-\             |
> > +	     |       \---/otherwise    |
> > +	     v 0xff                    |
> > +	   +----------+ otherwise      |
> > +	   |     1    |--------------->*
> > +	   |          |                ^
> > +	   +----------+                |
> > +	     |                         |
> > +	     v 0xff                    |
> > +	   +----------+<-\0xff         |
> > +	/->|          |--/             |
> > +	|  |     2    |--------------->*
> > +	|  |          | otherwise      ^
> > +	|  +----------+                |
> > +	|    |                         |
> > +	|    v 0x00                    |
> > +	|  +----------+                |
> > +	|  |     3    |                |
> > +	|  |          |--------------->*
> > +	|  +----------+ otherwise      ^
> > +	|    |                         |
> > +   0xff |    v 0xff                    |
> > +	|  +----------+                |
> > +	\--|     4    |                |
> > +	   |          |----------------/
> > +	   +----------+ otherwise
> > +	     |
> > +	     v 0x96
> > +	   +----------+
> > +	   |  FOUND   |
> > +	   +----------+
> > +*/
> > +
> >  static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
> >  					unsigned char *m, int len)
> >  {
> > @@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc
> > 
> >  	/* Search for the SOF marker (fixed part) in the header */
> >  	for (i = 0; i < len; i++) {
> > -		if (m[i] == pac_sof_marker[sd->sof_read]) {
> > -			sd->sof_read++;
> > -			if (sd->sof_read == sizeof(pac_sof_marker)) {
> > +		switch (sd->sof_read) {
> > +		case 0:
> > +			if (m[i] == 0xff)
> > +				sd->sof_read = 1;
> > +			break;
> > +		case 1:
> > +			if (m[i] == 0xff)
> > +				sd->sof_read = 2;
> > +			else
> > +				sd->sof_read = 0;
> > +			break;
> > +		case 2:
> > +			switch (m[i]) {
> > +			case 0x00:
> > +				sd->sof_read = 3;
> > +				break;
> > +			case 0xff:
> > +				/* stay in this state */
> > +				break;
> > +			default:
> > +				sd->sof_read = 0;
> > +			}
> > +			break;
> > +		case 3:
> > +			if (m[i] == 0xff)
> > +				sd->sof_read = 4;
> > +			else
> > +				sd->sof_read = 0;
> > +			break;
> > +		case 4:
> > +			switch (m[i]) {
> > +			case 0x96:
> > +				/* Pattern found */
> >  				PDEBUG(D_FRAM,
> >  					"SOF found, bytes to analyze: %u."
> >  					" Frame starts at byte #%u",
> >  					len, i + 1);
> >  				sd->sof_read = 0;
> >  				return m + i + 1;
> > +				break;
> > +			case 0xff:
> > +				sd->sof_read = 2;
> > +				break;
> > +			default:
> > +				sd->sof_read = 0;
> >  			}
> > -		} else {
> > +			break;
> > +		default:
> >  			sd->sof_read = 0;
> >  		}
> >  	}
> > 
> 
> ------------------------------------------------------------------------------
> Come build with us! The BlackBerry&reg; Developer Conference in SF, CA
> is the only developer event you need to attend this year. Jumpstart your
> developing skills, take BlackBerry mobile applications to market and stay 
> ahead of the curve. Join us from November 9&#45;12, 2009. Register now&#33;
> http://p.sf.net/sfu/devconf
> _______________________________________________ Ltp-list mailing list Ltp-list@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/ltp-list


^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [LTP] [PATCH] pac_common: redesign function for finding Start Of Frame
  2009-10-04 20:55 ` Németh Márton
@ 2009-10-05  7:32   ` Hans de Goede
  -1 siblings, 0 replies; 8+ messages in thread
From: Hans de Goede @ 2009-10-05  7:32 UTC (permalink / raw)
  To: Németh Márton
  Cc: Jean-Francois Moine, ltp-list, LKML, Theodore Kilgore,
	Thomas Kaiser, Kyle Guinn, V4L Mailing List

Hi,

Good one,

Acked-by: Hans de Goede <hdegoede@redhat.com>

Jean-Francois, can you please add this patch to your tree?

Thanks,

Hans


On 10/04/2009 10:55 PM, Németh Márton wrote:
> From: Márton Németh<nm127@freemail.hu>
>
> The original implementation of pac_find_sof() does not always find
> the Start Of Frame (SOF) marker. Replace it with a state machine
> based design.
>
> The change was tested with Labtec Webcam 2200.
>
> Signed-off-by: Márton Németh<nm127@freemail.hu>
> ---
> --- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
> +++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
> @@ -33,6 +33,45 @@
>   static const unsigned char pac_sof_marker[5] =
>   		{ 0xff, 0xff, 0x00, 0xff, 0x96 };
>
> +/*
> +   The following state machine finds the SOF marker sequence
> +   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
> +
> +	   +----------+
> +	   | 0: START |<---------------\
> +	   +----------+<-\             |
> +	     |       \---/otherwise    |
> +	     v 0xff                    |
> +	   +----------+ otherwise      |
> +	   |     1    |--------------->*
> +	   |          |                ^
> +	   +----------+                |
> +	     |                         |
> +	     v 0xff                    |
> +	   +----------+<-\0xff         |
> +	/->|          |--/             |
> +	|  |     2    |--------------->*
> +	|  |          | otherwise      ^
> +	|  +----------+                |
> +	|    |                         |
> +	|    v 0x00                    |
> +	|  +----------+                |
> +	|  |     3    |                |
> +	|  |          |--------------->*
> +	|  +----------+ otherwise      ^
> +	|    |                         |
> +   0xff |    v 0xff                    |
> +	|  +----------+                |
> +	\--|     4    |                |
> +	   |          |----------------/
> +	   +----------+ otherwise
> +	     |
> +	     v 0x96
> +	   +----------+
> +	   |  FOUND   |
> +	   +----------+
> +*/
> +
>   static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
>   					unsigned char *m, int len)
>   {
> @@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc
>
>   	/* Search for the SOF marker (fixed part) in the header */
>   	for (i = 0; i<  len; i++) {
> -		if (m[i] == pac_sof_marker[sd->sof_read]) {
> -			sd->sof_read++;
> -			if (sd->sof_read == sizeof(pac_sof_marker)) {
> +		switch (sd->sof_read) {
> +		case 0:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 1;
> +			break;
> +		case 1:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 2;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 2:
> +			switch (m[i]) {
> +			case 0x00:
> +				sd->sof_read = 3;
> +				break;
> +			case 0xff:
> +				/* stay in this state */
> +				break;
> +			default:
> +				sd->sof_read = 0;
> +			}
> +			break;
> +		case 3:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 4;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 4:
> +			switch (m[i]) {
> +			case 0x96:
> +				/* Pattern found */
>   				PDEBUG(D_FRAM,
>   					"SOF found, bytes to analyze: %u."
>   					" Frame starts at byte #%u",
>   					len, i + 1);
>   				sd->sof_read = 0;
>   				return m + i + 1;
> +				break;
> +			case 0xff:
> +				sd->sof_read = 2;
> +				break;
> +			default:
> +				sd->sof_read = 0;
>   			}
> -		} else {
> +			break;
> +		default:
>   			sd->sof_read = 0;
>   		}
>   	}
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

------------------------------------------------------------------------------
Come build with us! The BlackBerry&reg; Developer Conference in SF, CA
is the only developer event you need to attend this year. Jumpstart your
developing skills, take BlackBerry mobile applications to market and stay 
ahead of the curve. Join us from November 9&#45;12, 2009. Register now&#33;
http://p.sf.net/sfu/devconf
_______________________________________________
Ltp-list mailing list
Ltp-list@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/ltp-list

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] pac_common: redesign function for finding Start Of Frame
@ 2009-10-05  7:32   ` Hans de Goede
  0 siblings, 0 replies; 8+ messages in thread
From: Hans de Goede @ 2009-10-05  7:32 UTC (permalink / raw)
  To: Németh Márton
  Cc: Jean-Francois Moine, Thomas Kaiser, Kyle Guinn, Theodore Kilgore,
	V4L Mailing List, LKML, ltp-list

Hi,

Good one,

Acked-by: Hans de Goede <hdegoede@redhat.com>

Jean-Francois, can you please add this patch to your tree?

Thanks,

Hans


On 10/04/2009 10:55 PM, Németh Márton wrote:
> From: Márton Németh<nm127@freemail.hu>
>
> The original implementation of pac_find_sof() does not always find
> the Start Of Frame (SOF) marker. Replace it with a state machine
> based design.
>
> The change was tested with Labtec Webcam 2200.
>
> Signed-off-by: Márton Németh<nm127@freemail.hu>
> ---
> --- linux-2.6.32-rc1.orig/drivers/media/video/gspca/pac_common.h	2009-09-10 00:13:59.000000000 +0200
> +++ linux-2.6.32-rc1/drivers/media/video/gspca/pac_common.h	2009-10-04 21:49:19.000000000 +0200
> @@ -33,6 +33,45 @@
>   static const unsigned char pac_sof_marker[5] =
>   		{ 0xff, 0xff, 0x00, 0xff, 0x96 };
>
> +/*
> +   The following state machine finds the SOF marker sequence
> +   0xff, 0xff, 0x00, 0xff, 0x96 in a byte stream.
> +
> +	   +----------+
> +	   | 0: START |<---------------\
> +	   +----------+<-\             |
> +	     |       \---/otherwise    |
> +	     v 0xff                    |
> +	   +----------+ otherwise      |
> +	   |     1    |--------------->*
> +	   |          |                ^
> +	   +----------+                |
> +	     |                         |
> +	     v 0xff                    |
> +	   +----------+<-\0xff         |
> +	/->|          |--/             |
> +	|  |     2    |--------------->*
> +	|  |          | otherwise      ^
> +	|  +----------+                |
> +	|    |                         |
> +	|    v 0x00                    |
> +	|  +----------+                |
> +	|  |     3    |                |
> +	|  |          |--------------->*
> +	|  +----------+ otherwise      ^
> +	|    |                         |
> +   0xff |    v 0xff                    |
> +	|  +----------+                |
> +	\--|     4    |                |
> +	   |          |----------------/
> +	   +----------+ otherwise
> +	     |
> +	     v 0x96
> +	   +----------+
> +	   |  FOUND   |
> +	   +----------+
> +*/
> +
>   static unsigned char *pac_find_sof(struct gspca_dev *gspca_dev,
>   					unsigned char *m, int len)
>   {
> @@ -41,17 +80,54 @@ static unsigned char *pac_find_sof(struc
>
>   	/* Search for the SOF marker (fixed part) in the header */
>   	for (i = 0; i<  len; i++) {
> -		if (m[i] == pac_sof_marker[sd->sof_read]) {
> -			sd->sof_read++;
> -			if (sd->sof_read == sizeof(pac_sof_marker)) {
> +		switch (sd->sof_read) {
> +		case 0:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 1;
> +			break;
> +		case 1:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 2;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 2:
> +			switch (m[i]) {
> +			case 0x00:
> +				sd->sof_read = 3;
> +				break;
> +			case 0xff:
> +				/* stay in this state */
> +				break;
> +			default:
> +				sd->sof_read = 0;
> +			}
> +			break;
> +		case 3:
> +			if (m[i] == 0xff)
> +				sd->sof_read = 4;
> +			else
> +				sd->sof_read = 0;
> +			break;
> +		case 4:
> +			switch (m[i]) {
> +			case 0x96:
> +				/* Pattern found */
>   				PDEBUG(D_FRAM,
>   					"SOF found, bytes to analyze: %u."
>   					" Frame starts at byte #%u",
>   					len, i + 1);
>   				sd->sof_read = 0;
>   				return m + i + 1;
> +				break;
> +			case 0xff:
> +				sd->sof_read = 2;
> +				break;
> +			default:
> +				sd->sof_read = 0;
>   			}
> -		} else {
> +			break;
> +		default:
>   			sd->sof_read = 0;
>   		}
>   	}
> --
> To unsubscribe from this list: send the line "unsubscribe linux-media" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2009-10-13 14:44 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2009-10-04 20:55 [LTP] [PATCH] pac_common: redesign function for finding Start Of Frame Németh Márton
2009-10-04 20:55 ` Németh Márton
2009-10-04 20:56 ` [LTP] " Németh Márton
2009-10-04 20:56   ` Németh Márton
2009-10-13 14:43   ` [LTP] " Subrata Modak
2009-10-13 14:43     ` Subrata Modak
2009-10-05  7:32 ` Hans de Goede
2009-10-05  7:32   ` Hans de Goede

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