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stream_encoder.c : Improve fix for arithmetic overflow.

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The previous fix (patch 6f7ec60c) had the undesireable effect of slowing
down encoding speed on 16 bit files where the arithmetic overflow was
less likely to happen.

This fix forces the use of a FLAC__uint64 accumulator for 24 bit files
and restores the use of a FLAC_uint32 accumulator for 16 (and less) bit
files.

Unfortunately, I have not been able to prove to myself that this overflow
*cannot* happen with 16 bit files.
This commit is contained in:
Erik de Castro Lopo 2013-07-21 20:38:33 +10:00
parent dd9460e7a5
commit f34f31dac0
1 changed files with 3 additions and 3 deletions
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6
src/libFLAC/stream_encoder.c
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@ -3772,7 +3772,7 @@ void precompute_partition_info_sums_(
#if defined(FLAC__CPU_IA32) && !defined FLAC__NO_ASM && defined FLAC__HAS_NASM
/* slightly pessimistic but still catches all common cases */
/* WATCHOUT: "+ bps" is an assumption that the average residual magnitude will not be more than "bps" bits */
if(FLAC__bitmath_ilog2(default_partition_samples) + bps < 32) {
if(bps < 24 && FLAC__bitmath_ilog2(default_partition_samples) + bps < 32) {
precompute_partition_info_sums_32bit_asm_ia32_(residual, abs_residual_partition_sums, residual_samples + predictor_order, predictor_order, min_partition_order, max_partition_order);
return;
}
@ -3783,8 +3783,8 @@ void precompute_partition_info_sums_(
unsigned partition, residual_sample, end = (unsigned)(-(int)predictor_order);
/* slightly pessimistic but still catches all common cases */
/* WATCHOUT: "+ bps" is an assumption that the average residual magnitude will not be more than "bps" bits */
if(FLAC__bitmath_ilog2(default_partition_samples) + bps < 32) {
FLAC__uint64 abs_residual_partition_sum;
if(bps < 24 && FLAC__bitmath_ilog2(default_partition_samples) + bps < 32) {
FLAC__uint32 abs_residual_partition_sum;
for(partition = residual_sample = 0; partition < partitions; partition++) {
end += default_partition_samples;