added warning about use of REG_SCRATCH

diff --git a/src/mesa/tnl/t_vb_arbprogram.h b/src/mesa/tnl/t_vb_arbprogram.h
index 02cd432825cc0d546bf3f7eded696b1b2e9a11a6..92ae46113f18a8fa500ee355a1ec034914f09bba 100644 (file)
--- a/src/mesa/tnl/t_vb_arbprogram.h
+++ b/src/mesa/tnl/t_vb_arbprogram.h
@@ -65,7 +65,7 @@
 #define REG_NEG    67          /* -1,-1,-1,-1 */
 #define REG_LIT    68           /* 1,0,0,1 */
 #define REG_LIT2    69           /* 1,0,0,1 */
-#define REG_SCRATCH 70         /* internal temporary */
+#define REG_SCRATCH 70         /* internal temporary. XXX we can't actually use this because 70 doesn't fit in the 5-bit 'dst' instruction field! */
 #define REG_UNDEF  127         /* special case - never used */
 #define REG_MAX    128
 #define REG_INVALID ~0