Mesa (master): mesa: use ffs() to shorten loop in _mesa_drawbuffers()
Brian Paul
brianp at kemper.freedesktop.org
Tue Nov 3 16:53:23 UTC 2009
Module: Mesa
Branch: master
Commit: b28c637382cd3c3fcd54cd77062dab3df78230a9
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=b28c637382cd3c3fcd54cd77062dab3df78230a9
Author: Brian Paul <brianp at vmware.com>
Date: Mon Nov 2 13:20:19 2009 -0700
mesa: use ffs() to shorten loop in _mesa_drawbuffers()
---
src/mesa/main/buffers.c | 16 ++++++++++------
1 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/src/mesa/main/buffers.c b/src/mesa/main/buffers.c
index b5acda8..cdd16a8 100644
--- a/src/mesa/main/buffers.c
+++ b/src/mesa/main/buffers.c
@@ -375,15 +375,19 @@ _mesa_drawbuffers(GLcontext *ctx, GLuint n, const GLenum *buffers,
destMask = mask;
}
+ /*
+ * If n==1, destMask[0] may have up to four bits set.
+ * Otherwise, destMask[x] can only have one bit set.
+ */
if (n == 1) {
- GLuint buf, count = 0;
+ GLuint count = 0, destMask0 = destMask[0];
/* init to -1 to help catch errors */
fb->_ColorDrawBufferIndexes[0] = -1;
- for (buf = 0; buf < BUFFER_COUNT; buf++) {
- if (destMask[0] & (1 << buf)) {
- fb->_ColorDrawBufferIndexes[count] = buf;
- count++;
- }
+ while (destMask0) {
+ GLint bufIndex = _mesa_ffs(destMask0) - 1;
+ fb->_ColorDrawBufferIndexes[count] = bufIndex;
+ count++;
+ destMask0 &= ~(1 << bufIndex);
}
fb->ColorDrawBuffer[0] = buffers[0];
fb->_NumColorDrawBuffers = count;
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