diff options
author | Avi Kivity <avi@redhat.com> | 2012-01-03 15:32:57 +0200 |
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committer | Anthony Liguori <aliguori@us.ibm.com> | 2012-01-12 10:03:28 -0600 |
commit | a0f426109e17d579c2712f5b96a50215e6cc06a4 (patch) | |
tree | 772b9cbe1226cce709b5ae86b0e4466e589ca678 | |
parent | 19bf7c87081835449d5683ecb0858255bf5a0546 (diff) | |
download | qemu-a0f426109e17d579c2712f5b96a50215e6cc06a4.zip qemu-a0f426109e17d579c2712f5b96a50215e6cc06a4.tar.gz qemu-a0f426109e17d579c2712f5b96a50215e6cc06a4.tar.bz2 |
vga: optimize ppm_save() divisions
ppm_save() spends upwards of 50% of its time doing divisions. Replace them
with shifts.
Reviewed-by: Alon Levy <alevy@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
-rw-r--r-- | hw/vga.c | 10 |
1 files changed, 4 insertions, 6 deletions
@@ -2373,12 +2373,10 @@ int ppm_save(const char *filename, struct DisplaySurface *ds) v = *(uint32_t *)d; else v = (uint32_t) (*(uint16_t *)d); - r = ((v >> ds->pf.rshift) & ds->pf.rmax) * 256 / - (ds->pf.rmax + 1); - g = ((v >> ds->pf.gshift) & ds->pf.gmax) * 256 / - (ds->pf.gmax + 1); - b = ((v >> ds->pf.bshift) & ds->pf.bmax) * 256 / - (ds->pf.bmax + 1); + /* Limited to 8 or fewer bits per channel: */ + r = ((v >> ds->pf.rshift) & ds->pf.rmax) << (8 - ds->pf.rbits); + g = ((v >> ds->pf.gshift) & ds->pf.gmax) << (8 - ds->pf.gbits); + b = ((v >> ds->pf.bshift) & ds->pf.bmax) << (8 - ds->pf.bbits); *pbuf++ = r; *pbuf++ = g; *pbuf++ = b; |