[Qemu-devel] [6737] Sparse fixes: truncation by cast

[Qemu-devel] [6737] Sparse fixes: truncation by cast

[Blue Swirl]

Revision: 6737
          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6737
Author:   blueswir1
Date:     2009-03-07 15:46:23 +0000 (Sat, 07 Mar 2009)
Log Message:
-----------
Sparse fixes: truncation by cast

Fix Sparse warnings about constant truncation caused by cast

Modified Paths:
--------------
    trunk/bswap.h
    trunk/hw/ide.c
    trunk/hw/vga.c
    trunk/tcg/x86_64/tcg-target.c

Modified: trunk/bswap.h
===================================================================
--- trunk/bswap.h	2009-03-07 15:32:56 UTC (rev 6736)
+++ trunk/bswap.h	2009-03-07 15:46:23 UTC (rev 6737)
@@ -151,7 +151,7 @@
 {
     uint8_t *p1 = (uint8_t *)p;
 
-    p1[0] = v;
+    p1[0] = v & 0xff;
     p1[1] = v >> 8;
 }
 
@@ -159,7 +159,7 @@
 {
     uint8_t *p1 = (uint8_t *)p;
 
-    p1[0] = v;
+    p1[0] = v & 0xff;
     p1[1] = v >> 8;
     p1[2] = v >> 16;
     p1[3] = v >> 24;
@@ -188,7 +188,7 @@
     uint8_t *p1 = (uint8_t *)p;
 
     p1[0] = v >> 8;
-    p1[1] = v;
+    p1[1] = v & 0xff;
 }
 
 static inline void cpu_to_be32wu(uint32_t *p, uint32_t v)
@@ -198,7 +198,7 @@
     p1[0] = v >> 24;
     p1[1] = v >> 16;
     p1[2] = v >> 8;
-    p1[3] = v;
+    p1[3] = v & 0xff;
 }
 
 #endif

Modified: trunk/hw/ide.c
===================================================================
--- trunk/hw/ide.c	2009-03-07 15:32:56 UTC (rev 6736)
+++ trunk/hw/ide.c	2009-03-07 15:46:23 UTC (rev 6737)
@@ -1210,7 +1210,7 @@
 static inline void cpu_to_ube16(uint8_t *buf, int val)
 {
     buf[0] = val >> 8;
-    buf[1] = val;
+    buf[1] = val & 0xff;
 }
 
 static inline void cpu_to_ube32(uint8_t *buf, unsigned int val)
@@ -1218,7 +1218,7 @@
     buf[0] = val >> 24;
     buf[1] = val >> 16;
     buf[2] = val >> 8;
-    buf[3] = val;
+    buf[3] = val & 0xff;
 }
 
 static inline int ube16_to_cpu(const uint8_t *buf)

Modified: trunk/hw/vga.c
===================================================================
--- trunk/hw/vga.c	2009-03-07 15:32:56 UTC (rev 6736)
+++ trunk/hw/vga.c	2009-03-07 15:46:23 UTC (rev 6737)
@@ -38,33 +38,33 @@
 
 /* force some bits to zero */
 const uint8_t sr_mask[8] = {
-    (uint8_t)~0xfc,
-    (uint8_t)~0xc2,
-    (uint8_t)~0xf0,
-    (uint8_t)~0xc0,
-    (uint8_t)~0xf1,
-    (uint8_t)~0xff,
-    (uint8_t)~0xff,
-    (uint8_t)~0x00,
+    0x03,
+    0x3d,
+    0x0f,
+    0x3f,
+    0x0e,
+    0x00,
+    0x00,
+    0xff,
 };
 
 const uint8_t gr_mask[16] = {
-    (uint8_t)~0xf0, /* 0x00 */
-    (uint8_t)~0xf0, /* 0x01 */
-    (uint8_t)~0xf0, /* 0x02 */
-    (uint8_t)~0xe0, /* 0x03 */
-    (uint8_t)~0xfc, /* 0x04 */
-    (uint8_t)~0x84, /* 0x05 */
-    (uint8_t)~0xf0, /* 0x06 */
-    (uint8_t)~0xf0, /* 0x07 */
-    (uint8_t)~0x00, /* 0x08 */
-    (uint8_t)~0xff, /* 0x09 */
-    (uint8_t)~0xff, /* 0x0a */
-    (uint8_t)~0xff, /* 0x0b */
-    (uint8_t)~0xff, /* 0x0c */
-    (uint8_t)~0xff, /* 0x0d */
-    (uint8_t)~0xff, /* 0x0e */
-    (uint8_t)~0xff, /* 0x0f */
+    0x0f, /* 0x00 */
+    0x0f, /* 0x01 */
+    0x0f, /* 0x02 */
+    0x1f, /* 0x03 */
+    0x03, /* 0x04 */
+    0x7b, /* 0x05 */
+    0x0f, /* 0x06 */
+    0x0f, /* 0x07 */
+    0xff, /* 0x08 */
+    0x00, /* 0x09 */
+    0x00, /* 0x0a */
+    0x00, /* 0x0b */
+    0x00, /* 0x0c */
+    0x00, /* 0x0d */
+    0x00, /* 0x0e */
+    0x00, /* 0x0f */
 };
 
 #define cbswap_32(__x) \

Modified: trunk/tcg/x86_64/tcg-target.c
===================================================================
--- trunk/tcg/x86_64/tcg-target.c	2009-03-07 15:32:56 UTC (rev 6736)
+++ trunk/tcg/x86_64/tcg-target.c	2009-03-07 15:46:23 UTC (rev 6737)
@@ -243,7 +243,7 @@
     }
     if (opc & P_EXT)
         tcg_out8(s, 0x0f);
-    tcg_out8(s, opc);
+    tcg_out8(s, opc & 0xff);
 }
 
 static inline void tcg_out_modrm(TCGContext *s, int opc, int r, int rm)

Re: [Qemu-devel] [6737] Sparse fixes: truncation by cast

[Luca Tettamanti]

On Sat, Mar 7, 2009 at 4:46 PM, Blue Swirl <blauwirbel@gmail.com> wrote:
> Revision: 6737
>          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6737
> Author:   blueswir1
> Date:     2009-03-07 15:46:23 +0000 (Sat, 07 Mar 2009)
> Log Message:
> -----------
> Sparse fixes: truncation by cast
>
> Fix Sparse warnings about constant truncation caused by cast
>
> Modified: trunk/bswap.h
> ===================================================================
> --- trunk/bswap.h       2009-03-07 15:32:56 UTC (rev 6736)
> +++ trunk/bswap.h       2009-03-07 15:46:23 UTC (rev 6737)
> @@ -151,7 +151,7 @@
>  {
>     uint8_t *p1 = (uint8_t *)p;
>
> -    p1[0] = v;
> +    p1[0] = v & 0xff;
>     p1[1] = v >> 8;

Hum, by the same principle the last line should be:
p1[1] = (v >> 8) & 0xff;
no?

Luca

Re: [Qemu-devel] [6737] Sparse fixes: truncation by cast

[Blue Swirl]

On 3/7/09, Luca Tettamanti <kronos.it@gmail.com> wrote:
> On Sat, Mar 7, 2009 at 4:46 PM, Blue Swirl <blauwirbel@gmail.com> wrote:
>  > Revision: 6737
>  >          http://svn.sv.gnu.org/viewvc/?view=rev&root=qemu&revision=6737
>  > Author:   blueswir1
>  > Date:     2009-03-07 15:46:23 +0000 (Sat, 07 Mar 2009)
>  > Log Message:
>  > -----------
>  > Sparse fixes: truncation by cast
>  >
>  > Fix Sparse warnings about constant truncation caused by cast
>  >
>
> > Modified: trunk/bswap.h
>  > ===================================================================
>  > --- trunk/bswap.h       2009-03-07 15:32:56 UTC (rev 6736)
>  > +++ trunk/bswap.h       2009-03-07 15:46:23 UTC (rev 6737)
>  > @@ -151,7 +151,7 @@
>  >  {
>  >     uint8_t *p1 = (uint8_t *)p;
>  >
>  > -    p1[0] = v;
>  > +    p1[0] = v & 0xff;
>  >     p1[1] = v >> 8;
>
>
> Hum, by the same principle the last line should be:
>  p1[1] = (v >> 8) & 0xff;
>  no?

Maybe and there would be other similar places, but there is no warning
from Sparse except for this. Instead of "fix" I should have used
something like "suppress" because the code wasn't broken, it's just
that now Sparse is much more silent and real warnings are more visible
from the noise.