r600g: use maths instead of a loop to work out mask.

This is equivalent results with less looping.

Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/src/gallium/drivers/r600/r600_state_common.c b/src/gallium/drivers/r600/r600_state_common.c
index 0fe0e3d5d6762dd1f59381f298c6b3ddc5260e47..30c61817a08c82754e08c42492bf691203718e8d 100644 (file)
--- a/src/gallium/drivers/r600/r600_state_common.c
+++ b/src/gallium/drivers/r600/r600_state_common.c
@@ -576,10 +576,7 @@ void r600_draw_vbo(struct pipe_context *ctx, const struct pipe_draw_info *info)
        if (rctx->alpha_ref_dirty)
                r600_update_alpha_ref(rctx);
 
-       mask = 0;
-       for (int i = 0; i < rctx->framebuffer.nr_cbufs; i++) {
-               mask |= (0xF << (i * 4));
-       }
+       mask = (1ULL << ((unsigned)rctx->framebuffer.nr_cbufs * 4)) - 1;
 
        if (rctx->vgt.id != R600_PIPE_STATE_VGT) {
                rctx->vgt.id = R600_PIPE_STATE_VGT;