[parisc-linux] __arch__swab24()

[parisc-linux] __arch__swab24()

[LaMont Jones]

The following patch implements __arch__swab24() optimally for hppa.

It also has the side effect of making some other things happier. :-)

Any comments before I commit it to 2.4 and 2.5?

lamont

Index: include/asm-parisc/byteorder.h
===================================================================
RCS file: /var/cvs/linux/include/asm-parisc/byteorder.h,v
retrieving revision 1.7
diff -u -r1.7 byteorder.h
--- include/asm-parisc/byteorder.h	8 Jul 2003 16:50:09 -0000	1.7
+++ include/asm-parisc/byteorder.h	1 Aug 2003 16:25:00 -0000
@@ -14,6 +14,17 @@
 	return x;
 }
 
+static __inline__ __const__ __u32 ___arch__swab24(__u32 x)
+{
+	unsigned int temp;
+	__asm__("shd %0, %0, 8, %1\n\t"		/* shift xabcxabc -> cxab */
+		"dep %1, 15, 8, %1\n\t"		/* deposit cxab -> cbab */
+		"shd %r0, %1, 8, %0"		/* shift 0000cbab -> 0cba */
+		: "=r" (x), "=&r" (temp)
+		: "0" (x));
+	return x;
+}
+
 static __inline__ __const__ __u32 ___arch__swab32(__u32 x)
 {
 	unsigned int temp;
@@ -63,6 +74,7 @@
 #endif
 
 #define __arch__swab16(x) ___arch__swab16(x)
+#define __arch__swab24(x) ___arch__swab24(x)
 #define __arch__swab32(x) ___arch__swab32(x)
 
 #endif /* __GNUC__ */

Re: [parisc-linux] __arch__swab24()

[Matthew Wilcox]

On Fri, Aug 01, 2003 at 10:22:55AM -0600, LaMont Jones wrote:
> Any comments before I commit it to 2.4 and 2.5?

Here's what I came up with based on your patch.  It's embedded in a
test program.

#include <stdio.h>

typedef int __u32;

static int vanilla_swab24(int i)
{
        return ((i & 0xff) << 16) | (i & 0xff00) | ((i & 0xff0000) >> 16);
}

static __inline__ __const__ __u32 ___arch__swab24(__u32 x)
{
        __asm__("shd %0, %0, 8, %0\n\t"         /* shift xabcxabc -> cxab */
                "dep %0, 15, 8, %0\n\t"         /* deposit cxab -> cbab */
                "shd %%r0, %0, 8, %0"           /* shift 0000cbab -> 0cba */
                : "=r" (x)
                : "0" (x));
        return x;
}

int main(void)
{
        int i; 
        for (i = 0; i < 0x1ffffff; i++) { 
                if (___arch__swab24(i) != vanilla_swab24(i))
                        printf("Problem with i = %d\n", i);
        }
        return 0;
}


-- 
"It's not Hollywood.  War is real, war is primarily not about defeat or
victory, it is about death.  I've seen thousands and thousands of dead bodies.
Do you think I want to have an academic debate on this subject?" -- Robert Fisk

Re: [parisc-linux] __arch__swab24()

[Joel Soete]

 
>> On Fri, Aug 01, 2003 at 10:22:55AM -0600, LaMont Jones wrote:
>> Any comments before I commit it to 2.4 and 2.5?
>
>Here's what I came up with based on your patch.  It's embedded in a
>test program.

[...]

? no pb on my b180 (32bits kernel 2.4.21-pa6)

Joel


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