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Code Issues Releases Wiki Activity

Bug 2443 - Mac/Linux: Old (PowerPC) projects open flat-lined or with corrupted display on Intel machines

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This commit is contained in:
James Crook 2020-05-24 13:40:03 +01:00
parent 35e88d995b
commit 00084a8f38
1 changed files with 23 additions and 2 deletions
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25
src/BlockFile.cpp
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@ -342,15 +342,36 @@ void BlockFile::FixSummary(void *data)
mSummaryInfo.fields != 3)
return;
// These pointers point into extra 'unused' preamble space in the
// .au file. WE are using that space for summary data.
float *summary64K = (float *)((char *)data + mSummaryInfo.offset64K);
float *summary256 = (float *)((char *)data + mSummaryInfo.offset256);
float min, max;
int bad;
// Bug 2433 fix
// Previosuly we computed min and max, and a discrepancy between 64K
// summary and 256 sample summary contributed towards indicating an
// error (a byte swapped .au file, probably from a machine
// with the opposite architecture).
//
// However, that min-max test was incorrect on two counts:
// 1. Both the 256 and 64K data streams are byte-swapped or not
// together - so a consistency check served no useful purpose.
// 2. On 64 bit architecture with function inlining, calculations
// could end up being done at higher precision on one variable,
// resulting in a spurious mismatch. Exact comparison of floats
// can be problematic.
//
// Point 2 led to bug 2433 when functions were inlined, and .au
// files not being byte swapped when they should be.
//
// The fix is to not use the min max in the consistency test, and just
// use the 'bad' count which is an integer. We aim for no bad samples.
ComputeMinMax256(summary256, &min, &max, &bad);
if (min != summary64K[0] || max != summary64K[1] || bad > 0) {
if ( bad > 0) {
unsigned int *buffer = (unsigned int *)data;
auto len = mSummaryInfo.totalSummaryBytes / 4;
@ -358,7 +379,7 @@ void BlockFile::FixSummary(void *data)
buffer[i] = wxUINT32_SWAP_ALWAYS(buffer[i]);
ComputeMinMax256(summary256, &min, &max, &bad);
if (min == summary64K[0] && max == summary64K[1] && bad == 0) {
if ( bad == 0) {
// The byte-swapping worked!
return;
}