[Mesa-dev] [PATCH 4/4] mesa: new BYTE/SHORT_TO_FLOATZ() macros

[Brian Paul]

Rather than redefining the BYTE/SHORT_TO_FLOAT macros, just define new
ones with different names.  These macros preserve zero when converting.
---
 src/mesa/main/image.c  |   16 ----------------
 src/mesa/main/macros.h |    7 +++++++
 src/mesa/main/pack.c   |   36 ++++++++++--------------------------
 3 files changed, 17 insertions(+), 42 deletions(-)

diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c
index cd333ab..ab89436 100644
--- a/src/mesa/main/image.c
+++ b/src/mesa/main/image.c
@@ -39,22 +39,6 @@
 #include "mtypes.h"
 
 
-/**
- * NOTE:
- * Normally, BYTE_TO_FLOAT(0) returns 0.00392  That causes problems when
- * we later convert the float to a packed integer value (such as for
- * GL_RGB5_A1) because we'll wind up with a non-zero value.
- *
- * We redefine the macros here so zero is handled correctly.
- */
-#undef BYTE_TO_FLOAT
-#define BYTE_TO_FLOAT(B)    ((B) == 0 ? 0.0F : ((2.0F * (B) + 1.0F) * (1.0F/255.0F)))
-
-#undef SHORT_TO_FLOAT
-#define SHORT_TO_FLOAT(S)   ((S) == 0 ? 0.0F : ((2.0F * (S) + 1.0F) * (1.0F/65535.0F)))
-
-
-
 
 /**
  * \return GL_TRUE if type is packed pixel type, GL_FALSE otherwise.
diff --git a/src/mesa/main/macros.h b/src/mesa/main/macros.h
index 029f609..dbe5b86 100644
--- a/src/mesa/main/macros.h
+++ b/src/mesa/main/macros.h
@@ -54,6 +54,10 @@ extern GLfloat _mesa_ubyte_to_float_color_tab[256];
 #define FLOAT_TO_BYTE(X)    ( (((GLint) (255.0F * (X))) - 1) / 2 )
 
 
+/** Convert GLbyte to GLfloat while preserving zero */
+#define BYTE_TO_FLOATZ(B)   ((B) == 0 ? 0.0F : BYTE_TO_FLOAT(B))
+
+
 /** Convert GLbyte in [-128,127] to GLfloat in [-1.0,1.0], texture/fb data */
 #define BYTE_TO_FLOAT_TEX(B)    ((B) == -128 ? -1.0F : (B) * (1.0F/127.0F))
 
@@ -73,6 +77,9 @@ extern GLfloat _mesa_ubyte_to_float_color_tab[256];
 /** Convert GLfloat in [-1.0,1.0] to GLshort in [-32768,32767] */
 #define FLOAT_TO_SHORT(X)   ( (((GLint) (65535.0F * (X))) - 1) / 2 )
 
+/** Convert GLshort to GLfloat while preserving zero */
+#define SHORT_TO_FLOATZ(S)   ((S) == 0 ? 0.0F : SHORT_TO_FLOAT(S))
+
 
 /** Convert GLshort in [-32768,32767] to GLfloat in [-1.0,1.0], texture/fb data */
 #define SHORT_TO_FLOAT_TEX(S)    ((S) == -32768 ? -1.0F : (S) * (1.0F/32767.0F))
diff --git a/src/mesa/main/pack.c b/src/mesa/main/pack.c
index a3cfb59..6f48a2e 100644
--- a/src/mesa/main/pack.c
+++ b/src/mesa/main/pack.c
@@ -44,22 +44,6 @@
 
 
 /**
- * NOTE:
- * Normally, BYTE_TO_FLOAT(0) returns 0.00392  That causes problems when
- * we later convert the float to a packed integer value (such as for
- * GL_RGB5_A1) because we'll wind up with a non-zero value.
- *
- * We redefine the macros here so zero is handled correctly.
- */
-#undef BYTE_TO_FLOAT
-#define BYTE_TO_FLOAT(B)    ((B) == 0 ? 0.0F : ((2.0F * (B) + 1.0F) * (1.0F/255.0F)))
-
-#undef SHORT_TO_FLOAT
-#define SHORT_TO_FLOAT(S)   ((S) == 0 ? 0.0F : ((2.0F * (S) + 1.0F) * (1.0F/65535.0F)))
-
-
-
-/**
  * Flip the 8 bits in each byte of the given array.
  *
  * \param p array.
@@ -2504,10 +2488,10 @@ extract_float_rgba(GLuint n, GLfloat rgba[][4],
          PROCESS(aSrc, ACOMP, 1.0F, 255, GLubyte, UBYTE_TO_FLOAT);
          break;
       case GL_BYTE:
-         PROCESS(rSrc, RCOMP, 0.0F,   0, GLbyte, BYTE_TO_FLOAT);
-         PROCESS(gSrc, GCOMP, 0.0F,   0, GLbyte, BYTE_TO_FLOAT);
-         PROCESS(bSrc, BCOMP, 0.0F,   0, GLbyte, BYTE_TO_FLOAT);
-         PROCESS(aSrc, ACOMP, 1.0F, 127, GLbyte, BYTE_TO_FLOAT);
+         PROCESS(rSrc, RCOMP, 0.0F,   0, GLbyte, BYTE_TO_FLOATZ);
+         PROCESS(gSrc, GCOMP, 0.0F,   0, GLbyte, BYTE_TO_FLOATZ);
+         PROCESS(bSrc, BCOMP, 0.0F,   0, GLbyte, BYTE_TO_FLOATZ);
+         PROCESS(aSrc, ACOMP, 1.0F, 127, GLbyte, BYTE_TO_FLOATZ);
          break;
       case GL_UNSIGNED_SHORT:
          PROCESS(rSrc, RCOMP, 0.0F,      0, GLushort, USHORT_TO_FLOAT);
@@ -2516,10 +2500,10 @@ extract_float_rgba(GLuint n, GLfloat rgba[][4],
          PROCESS(aSrc, ACOMP, 1.0F, 0xffff, GLushort, USHORT_TO_FLOAT);
          break;
       case GL_SHORT:
-         PROCESS(rSrc, RCOMP, 0.0F,     0, GLshort, SHORT_TO_FLOAT);
-         PROCESS(gSrc, GCOMP, 0.0F,     0, GLshort, SHORT_TO_FLOAT);
-         PROCESS(bSrc, BCOMP, 0.0F,     0, GLshort, SHORT_TO_FLOAT);
-         PROCESS(aSrc, ACOMP, 1.0F, 32767, GLshort, SHORT_TO_FLOAT);
+         PROCESS(rSrc, RCOMP, 0.0F,     0, GLshort, SHORT_TO_FLOATZ);
+         PROCESS(gSrc, GCOMP, 0.0F,     0, GLshort, SHORT_TO_FLOATZ);
+         PROCESS(bSrc, BCOMP, 0.0F,     0, GLshort, SHORT_TO_FLOATZ);
+         PROCESS(aSrc, ACOMP, 1.0F, 32767, GLshort, SHORT_TO_FLOATZ);
          break;
       case GL_UNSIGNED_INT:
          PROCESS(rSrc, RCOMP, 0.0F,          0, GLuint, UINT_TO_FLOAT);
@@ -4822,14 +4806,14 @@ _mesa_unpack_depth_span( struct gl_context *ctx, GLuint n,
     */
    switch (srcType) {
       case GL_BYTE:
-         DEPTH_VALUES(GLbyte, BYTE_TO_FLOAT);
+         DEPTH_VALUES(GLbyte, BYTE_TO_FLOATZ);
          needClamp = GL_TRUE;
          break;
       case GL_UNSIGNED_BYTE:
          DEPTH_VALUES(GLubyte, UBYTE_TO_FLOAT);
          break;
       case GL_SHORT:
-         DEPTH_VALUES(GLshort, SHORT_TO_FLOAT);
+         DEPTH_VALUES(GLshort, SHORT_TO_FLOATZ);
          needClamp = GL_TRUE;
          break;
       case GL_UNSIGNED_SHORT:
-- 
1.7.3.4