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Some fixes to the PC speaker - fixes amplitude in mode 1 (the intro of Perestroika now works correctly at least on the 8088 4.77 MHz) and makes the parameters consistent with the rest of the PC speaker emulation.

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OBattler
2019-11-11 06:07:50 +01:00
parent d3bdee4ae1
commit fa4890c9db
1 changed files with 33 additions and 4 deletions
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37
src/sound/snd_speaker.c
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@@ -1,3 +1,21 @@
/*
* 86Box A hypervisor and IBM PC system emulator that specializes in
* running old operating systems and software designed for IBM
* PC systems and compatibles from 1981 through fairly recent
* system designs based on the PCI bus.
*
* This file is part of the 86Box distribution.
*
* Emulation of the PC speaker.
*
* Version: @(#)snd_speaker.c 1.0.0 2019/11/11
*
* Authors: Sarah Walker, <http://pcem-emulator.co.uk/>
* Miran Grca, <mgrca8@gmail.com>
*
* Copyright 2008-2019 Sarah Walker.
* Copyright 2016-2019 Miran Grca.
*/
#include <stdio.h>
#include <stdint.h>
#include <string.h>
@@ -23,20 +41,31 @@ void
speaker_update(void)
{
int32_t val;
double timer2_count, amplitude;
timer2_count = pit.l[2] ? ((double) pit.l[2]) : 65536.0;
amplitude = ((timer2_count / 64.0) * 10240.0) - 5120.0;
if (amplitude > 5120.0)
amplitude = 5120.0;
if (speaker_pos >= sound_pos_global)
return;
for (; speaker_pos < sound_pos_global; speaker_pos++) {
if (speaker_gated && was_speaker_enable) {
if (!pit.m[2] || pit.m[2]==4)
val = speakval;
if ((pit.m[2] == 0) || (pit.m[2] == 4))
val = (int32_t) amplitude;
else if (pit.l[2] < 0x40)
val = 0xa00;
else
val = speakon ? 0x1400 : 0;
} else
val = was_speaker_enable ? 0x1400 : 0;
} else {
if (pit.m[2] == 1)
val = was_speaker_enable ? (int32_t) amplitude : 0;
else
val = was_speaker_enable ? 0x1400 : 0;
}
if (!speaker_enable)
was_speaker_enable = 0;