diff options
| -rw-r--r-- | palsa.c | 36 |
1 files changed, 35 insertions, 1 deletions
@@ -358,10 +358,44 @@ palsa_callback (char *stream, int len) { return; } int bytesread = streamer_read (stream, len); - int ivolume = volume_get_amp () * 1000; + +// FIXME: move volume control to streamer_read for copy optimization +#if 0 + int16_t vol[4]; + vol[0] = volume_get_amp () * 255; // that will be extra 8 bits + // pack 4 times + vol[1] = vol[2] = vol[3] = vol[0]; + + // apply volume with mmx + __asm__ volatile( + " mov %0, %%ecx\n\t" + " shr $4, %%ecx\n\t" + " mov %1, %%eax\n\t" + " movq %2, %mm1\n\t" + "1:\n\t" + " movq [%%eax], %mm0\n\t" + " movq %mm0, %mm2\n\t" + " movq %mm0, %mm3\n\t" + " pmullw %mm1, %mm2\n\t" + " pmulhw %mm1, %mm3\n\t" + " psrlw $8, %mm2\n\t" // discard lowest 8 bits + " psllw $8, %mm3\n\t" // shift left 8 lsbs of hiwords + " por %mm3, %mm2\n\t" // OR them together + " movq %mm3, [%%eax]\n\t" // load back to memory + " add $8, %%eax\n\t" + " dec %%ecx\n\t" + " jnz 1b\n\t" + : + : "r"(len), "r"(stream), "r"(vol) + : "%ecx", "%eax" + ); + +#else + int16_t ivolume = volume_get_amp () * 1000; for (int i = 0; i < bytesread/2; i++) { ((int16_t*)stream)[i] = (int16_t)(((int32_t)(((int16_t*)stream)[i])) * ivolume / 1000); } +#endif if (bytesread < len) { memset (stream + bytesread, 0, len-bytesread); } |