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Emulation of DAC charging, Fixes #46, #85, #88 and #89

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This commit is contained in:
Lior Halphon 2018-10-19 23:53:01 +03:00
parent 4276549acd
commit 3035f43428
2 changed files with 22 additions and 11 deletions
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24
Core/apu.c
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@ -75,9 +75,19 @@ static void render(GB_gameboy_t *gb, bool no_downsampling, GB_sample_t *dest)
gb->apu_output.dac_discharge[i] -= ((double) DAC_DECAY_SPEED) / gb->apu_output.sample_rate;
if (gb->apu_output.dac_discharge[i] < 0) {
multiplier = 0;
gb->apu_output.dac_discharge[i] = 0;
}
else {
multiplier *= pow(0.05, 1 - gb->apu_output.dac_discharge[i]) * (gb->apu_output.dac_discharge[i]);
multiplier *= gb->apu_output.dac_discharge[i];
}
}
else {
gb->apu_output.dac_discharge[i] += ((double) DAC_ATTACK_SPEED) / gb->apu_output.sample_rate;
if (gb->apu_output.dac_discharge[i] > 1) {
gb->apu_output.dac_discharge[i] = 1;
}
else {
multiplier *= gb->apu_output.dac_discharge[i];
}
}
@ -797,9 +807,10 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
gb->apu.wave_channel.length_enabled = false;
}
/* Note that we don't change the sample just yet! This was verified on hardware. */
/* Todo: The first sample *is not* skipped on the DMG, this is a bug introduced
on the CGB. It appears that the bug was fixed on the AGB, but it's not reflected
by PCM434. */
/* Todo: The first sample might *not* beskipped on the DMG, this could be a bug
introduced on the CGB. It appears that the bug was fixed on the AGB, but it's
not reflected by PCM34. This should be probably verified as this could just
mean differences in the DACs. */
/* Todo: Similar issues may apply to the other channels on the DMG/AGB, test, verify and fix if needed */
}
@ -939,11 +950,6 @@ void GB_apu_write(GB_gameboy_t *gb, uint8_t reg, uint8_t value)
}
}
gb->io_registers[reg] = value;
for (unsigned i = 0; i < GB_N_CHANNELS; i++) {
if (is_DAC_enabled(gb, i)) {
gb->apu_output.dac_discharge[i] = 1.0;
}
}
}
size_t GB_apu_get_current_buffer_length(GB_gameboy_t *gb)

9
Core/apu.h
View File

@ -8,8 +8,13 @@
#ifdef GB_INTERNAL
/* Speed = 1 / Length (in seconds) */
/* Todo: Measure this and find the actual curve shape*/
#define DAC_DECAY_SPEED 50
/* Todo: Measure these and find the actual curve shapes.
They are known to be incorrect (Some analog test ROM sound different),
but are good enough approximations to fix Cannon Fodder's terrible audio.
It also varies by model. */
#define DAC_DECAY_SPEED (1000000)
#define DAC_ATTACK_SPEED 1000
/* Divides nicely and never overflows with 4 channels and 8 (1-8) volume levels */
#ifdef WIIU