claunia/flac
1
0
Fork 0
mirror of https://github.com/claunia/flac.git synced 2025-12-16 18:54:26 +00:00
Code Issues Packages Projects Releases Wiki Activity

Attempt to fix differences between x86 FPU and SSE calculations.

Browse Source 
The x86 FPU holds intermediate results in larger registers than what
the SSE unit uses, resulting in slighlty different encodings of audio
data. Attempt to fix this by modifying libFLAC/lpc.c to store calculation
results in a FLAC__read before adding it to a sum.

At the moment this works, but I could easily imagine a new version of
the compiler optimising this store to the FLAC__real away leaving us
in the same situation we have now.

Patch-from: Oliver Stöneberg on sourceforge.net
Closes: https://sourceforge.net/p/flac/bugs/409/
This commit is contained in:
Erik de Castro Lopo
2014-03-21 19:25:55 +11:00
parent bc2b8c6e16
commit 70b078cfd5
1 changed files with 9 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files

14
src/libFLAC/lpc.c
View File

@@ -99,7 +99,7 @@ void FLAC__lpc_compute_autocorrelation(const FLAC__real data[], unsigned data_le
* this version tends to run faster because of better data locality * this version tends to run faster because of better data locality
* ('data_len' is usually much larger than 'lag') * ('data_len' is usually much larger than 'lag')
*/ */
FLAC__real d; FLAC__real d, tmp;
unsigned sample, coeff; unsigned sample, coeff;
const unsigned limit = data_len - lag; const unsigned limit = data_len - lag;
@@ -110,13 +110,17 @@ void FLAC__lpc_compute_autocorrelation(const FLAC__real data[], unsigned data_le
autoc[coeff] = 0.0; autoc[coeff] = 0.0;
for(sample = 0; sample <= limit; sample++) { for(sample = 0; sample <= limit; sample++) {
d = data[sample]; d = data[sample];
for(coeff = 0; coeff < lag; coeff++) for(coeff = 0; coeff < lag; coeff++) {
autoc[coeff] += d * data[sample+coeff]; tmp = d * data[sample+coeff];
autoc[coeff] += tmp;
}
} }
for(; sample < data_len; sample++) { for(; sample < data_len; sample++) {
d = data[sample]; d = data[sample];
for(coeff = 0; coeff < data_len - sample; coeff++) for(coeff = 0; coeff < data_len - sample; coeff++) {
autoc[coeff] += d * data[sample+coeff]; tmp = d * data[sample+coeff];
autoc[coeff] += tmp;
}
} }
} }