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random: Optimize Randomizer::getBytesFromString() #14894

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Merged
merged 3 commits into from
Jul 20, 2024
Merged

random: Optimize Randomizer::getBytesFromString() #14894

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65ea801
Changed calculate bitmask 8 bytes at a time.
SakiTakamachi Jul 11, 2024
f23980d
Optimized bit shifting
SakiTakamachi Jul 11, 2024
2fd607f
Improve clarity of the mask expansion
TimWolla Jul 20, 2024
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Improve clarity of the mask expansion
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@TimWolla
TimWolla authored Jul 20, 2024
commit 2fd607f96f615eac4a462ede37769ae12152f35a
6 changes: 3 additions & 3 deletions ext/random/randomizer.c
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Original file line number Diff line number Diff line change
Expand Up @@ -431,9 +431,9 @@ PHP_METHOD(Random_Randomizer, getBytesFromString)
mask |= mask >> 1;
mask |= mask >> 2;
mask |= mask >> 4;
// Expand the lowest byte into all bytes.
mask *= 0x0101010101010101;

/* Example: if mask is 0xAB, will be 0xABABABABABABABAB */
uint64_t mask_repeat = (~((uint64_t) 0) / 0xff) * mask;
int failures = 0;
while (total_size < length) {
php_random_result result = engine.algo->generate(engine.state);
Expand All @@ -442,7 +442,7 @@ PHP_METHOD(Random_Randomizer, getBytesFromString)
RETURN_THROWS();
}

uint64_t offsets = result.result & mask_repeat;
uint64_t offsets = result.result & mask;
for (size_t i = 0; i < result.size; i++) {
uint64_t offset = offsets & 0xff;
offsets >>= 8;
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