ref: a2ad39d0d2debea543b5e44df66a986caf45efdd
parent: 7fe7a353c680694c0223cee6cbdfce2199ed7608
author: Olav Sørensen <olav.sorensen@live.no>
date: Tue Dec 29 08:05:47 EST 2020
[x86/x86_64] Speed up linear interpolation resampler
--- a/src/mixer/ft2_mix_macros.h
+++ b/src/mixer/ft2_mix_macros.h
@@ -131,13 +131,19 @@
#define LINEAR_INTERPOLATION8(s, f) \
{ \- const double dFrac = (const double)((uint32_t)f * (1.0 / (UINT32_MAX+1.0))); /* 0.0 .. 0.999999999 */ \
+ /* uint32_t -> int32_t so that we can use SIMD for fast int->double conversion */ \
+ const int32_t frac = (uint32_t)(f) >> 1; /* (2^32)-1 -> (2^31)-1 */ \
+ \
+ const double dFrac = (double)(frac * (1.0 / (INT32_MAX+1.0))); /* 0.0 .. 0.999999999 */ \
dSample = ((s[0] + (s[1]-s[0]) * dFrac)) * (1.0 / 128.0); \
} \
#define LINEAR_INTERPOLATION16(s, f) \
{ \- const double dFrac = (const double)((uint32_t)f * (1.0 / (UINT32_MAX+1.0))); /* 0.0 .. 0.999999999 */ \
+ /* uint32_t -> int32_t so that we can use SIMD for fast int->double conversion */ \
+ const int32_t frac = (uint32_t)(f) >> 1; /* (2^32)-1 -> (2^31)-1 */ \
+ \
+ const double dFrac = (double)(frac * (1.0 / (INT32_MAX+1.0))); /* 0.0 .. 0.999999999 */ \
dSample = ((s[0] + (s[1]-s[0]) * dFrac)) * (1.0 / 32768.0); \
} \