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SM8521: don't use rand() 

issue #1004
This commit is contained in:
tildearrow 2023-03-01 15:15:17 -05:00
parent 9a439c248a
commit 814907c0a7
2 changed files with 9 additions and 2 deletions
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8
src/engine/platform/sound/sm8521.c
View File

@ -5,6 +5,9 @@
SM8521 sound emulator
by cam900
MODIFIED BY TILDEARROW
THIS IS NOT THE ORIGINAL VERSION
This file is licensed under zlib license.
============================================================================
@ -69,7 +72,8 @@ void sm8521_noise_tick(struct sm8521_noise_t *noise, const int cycle)
noise->base.counter += cycle;
while (noise->base.counter >= (noise->base.t + 1))
{
noise->lfsr = rand() & 0x1; // unknown algorithm
// unknown algorithm, but don't use rand()
noise->lfsr = ( noise->lfsr>>1|(((noise->lfsr) ^ (noise->lfsr >> 5) ^ (noise->lfsr >> 8) ^ (noise->lfsr >> 13) ) & 1)<<31);
noise->base.counter -= (noise->base.t + 1);
}
noise->base.out = (((noise->lfsr & 0x1) ? 7 : -8) * noise->base.level) >> 1; // scale out to 8bit
@ -125,7 +129,7 @@ void sm8521_reset(struct sm8521_t *sm8521)
sm8521->noise.base.level = 0;
sm8521->noise.base.out = 0;
sm8521->noise.base.counter = 0;
sm8521->noise.lfsr = 0;
sm8521->noise.lfsr = 0x89abcdef;
sm8521->out = 0;
sm8521->sgda = 0;
sm8521->sgc = 0;

3
src/engine/platform/sound/sm8521.h
View File

@ -5,6 +5,9 @@
SM8521 sound emulator
by cam900
MODIFIED BY TILDEARROW
THIS IS NOT THE ORIGINAL VERSION
This file is licensed under zlib license.
============================================================================