Mesa (10.4): mesa: Fix clamping to -1.0 in snorm_to_float

[Emil Velikov]

Module: Mesa
Branch: 10.4
Commit: a25e26f67f2479dff4c33885255e546a7869db1c
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=a25e26f67f2479dff4c33885255e546a7869db1c

Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date:   Sat Aug 23 08:36:46 2014 -0700

mesa: Fix clamping to -1.0 in snorm_to_float

This patch fixes the return of a wrong value when x is lower than
-MAX_INT(src_bits) as the result would not be between [-1.0 1.0].

v2 by Samuel Iglesias <siglesias at igalia.com>:
    - Modify snorm_to_float() to avoid doing the division when
      x == -MAX_INT(src_bits)

Cc: 10.4 <mesa-stable at lists.freedesktop.org>
Reviewed-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Jason Ekstrand <jason.ekstrand at intel.com>
(cherry picked from commit 7d1b08ac44cf2531b0df39f52ead93ad216ea233)

---

 src/mesa/main/format_utils.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/mesa/main/format_utils.c b/src/mesa/main/format_utils.c
index 93a0cea..5dd0848 100644
--- a/src/mesa/main/format_utils.c
+++ b/src/mesa/main/format_utils.c
@@ -152,7 +152,7 @@ unorm_to_float(unsigned x, unsigned src_bits)
 static inline float
 snorm_to_float(int x, unsigned src_bits)
 {
-   if (x == -MAX_INT(src_bits))
+   if (x <= -MAX_INT(src_bits))
       return -1.0f;
    else
       return x * (1.0f / (float)MAX_INT(src_bits));