From 05ff4d209d67962c6f367a94dcf0045ea242d5c3 Mon Sep 17 00:00:00 2001
From: Eric Anholt <eric@anholt.net>
Date: Tue, 24 Jan 2012 14:48:56 -0800
Subject: [PATCH] mesa: When unpacking signed integer pixel data, don't clamp
 to 0.

In the core, we always treat spans of int/uint data as uint, so this
extract function was truncating storage of integer pixel data to a n
int texture to (0, max_int) instead of (min_int, max_int).  There is
probably missing code for handling truncation on conversion between
pixel formats, still, but this does improve things.

NOTE: This is a candidate for the 8.0 branch.

Reviewed-by: Brian Paul <brianp@vmware.com>
(cherry picked from commit dadbec1e90415f0744eb91e684bf9d7496f474c0)
---
 src/mesa/main/pack.c | 45 ++++++++++++--------------------------------
 1 file changed, 12 insertions(+), 33 deletions(-)

diff --git a/src/mesa/main/pack.c b/src/mesa/main/pack.c
index 23e9d1d5b3e..ee983f90aab 100644
--- a/src/mesa/main/pack.c
+++ b/src/mesa/main/pack.c
@@ -3006,27 +3006,6 @@ extract_float_rgba(GLuint n, GLfloat rgba[][4],
 }
 
 
-static inline GLuint
-clamp_byte_to_uint(GLbyte b)
-{
-   return b < 0 ? 0 : b;
-}
-
-
-static inline GLuint
-clamp_short_to_uint(GLshort s)
-{
-   return s < 0 ? 0 : s;
-}
-
-
-static inline GLuint
-clamp_int_to_uint(GLint i)
-{
-   return i < 0 ? 0 : i;
-}
-
-
 static inline GLuint
 clamp_float_to_uint(GLfloat f)
 {
@@ -3149,10 +3128,10 @@ extract_uint_rgba(GLuint n, GLuint rgba[][4],
          PROCESS(aSrc, ACOMP, 1, GLubyte, (GLuint));
          break;
       case GL_BYTE:
-         PROCESS(rSrc, RCOMP, 0, GLbyte, clamp_byte_to_uint);
-         PROCESS(gSrc, GCOMP, 0, GLbyte, clamp_byte_to_uint);
-         PROCESS(bSrc, BCOMP, 0, GLbyte, clamp_byte_to_uint);
-         PROCESS(aSrc, ACOMP, 1, GLbyte, clamp_byte_to_uint);
+         PROCESS(rSrc, RCOMP, 0, GLbyte, (GLuint));
+         PROCESS(gSrc, GCOMP, 0, GLbyte, (GLuint));
+         PROCESS(bSrc, BCOMP, 0, GLbyte, (GLuint));
+         PROCESS(aSrc, ACOMP, 1, GLbyte, (GLuint));
          break;
       case GL_UNSIGNED_SHORT:
          PROCESS(rSrc, RCOMP, 0, GLushort, (GLuint));
@@ -3161,10 +3140,10 @@ extract_uint_rgba(GLuint n, GLuint rgba[][4],
          PROCESS(aSrc, ACOMP, 1, GLushort, (GLuint));
          break;
       case GL_SHORT:
-         PROCESS(rSrc, RCOMP, 0, GLshort, clamp_short_to_uint);
-         PROCESS(gSrc, GCOMP, 0, GLshort, clamp_short_to_uint);
-         PROCESS(bSrc, BCOMP, 0, GLshort, clamp_short_to_uint);
-         PROCESS(aSrc, ACOMP, 1, GLshort, clamp_short_to_uint);
+         PROCESS(rSrc, RCOMP, 0, GLshort, (GLuint));
+         PROCESS(gSrc, GCOMP, 0, GLshort, (GLuint));
+         PROCESS(bSrc, BCOMP, 0, GLshort, (GLuint));
+         PROCESS(aSrc, ACOMP, 1, GLshort, (GLuint));
          break;
       case GL_UNSIGNED_INT:
          PROCESS(rSrc, RCOMP, 0, GLuint, (GLuint));
@@ -3173,10 +3152,10 @@ extract_uint_rgba(GLuint n, GLuint rgba[][4],
          PROCESS(aSrc, ACOMP, 1, GLuint, (GLuint));
          break;
       case GL_INT:
-         PROCESS(rSrc, RCOMP, 0, GLint, clamp_int_to_uint);
-         PROCESS(gSrc, GCOMP, 0, GLint, clamp_int_to_uint);
-         PROCESS(bSrc, BCOMP, 0, GLint, clamp_int_to_uint);
-         PROCESS(aSrc, ACOMP, 1, GLint, clamp_int_to_uint);
+         PROCESS(rSrc, RCOMP, 0, GLint, (GLuint));
+         PROCESS(gSrc, GCOMP, 0, GLint, (GLuint));
+         PROCESS(bSrc, BCOMP, 0, GLint, (GLuint));
+         PROCESS(aSrc, ACOMP, 1, GLint, (GLuint));
          break;
       case GL_FLOAT:
          PROCESS(rSrc, RCOMP, 0, GLfloat, clamp_float_to_uint);