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Location: cpp/openttd-patchpack/source/src/mixer.cpp
r9334:6d079081ec24
2.6 KiB
text/x-c
(svn r13226) -Feature: Allow to have more than only two airports per town. The number of airports is now controlled by the noise each of them generates, the distance from town's center and how tolerant the town is.
Initial concept : TTDPatch (moreairpots), Initial code : Pasky
Thanks to BigBB (help coding), Smatz Skidd13 and frosch for bugcatches and advices
Initial concept : TTDPatch (moreairpots), Initial code : Pasky
Thanks to BigBB (help coding), Smatz Skidd13 and frosch for bugcatches and advices
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 | /* $Id$ */
/** @file mixer.cpp Mixing of sound samples. */
#include "stdafx.h"
#include "openttd.h"
#include "mixer.h"
struct MixerChannel {
bool active;
/* pointer to allocated buffer memory */
int8 *memory;
/* current position in memory */
uint32 pos;
uint32 frac_pos;
uint32 frac_speed;
uint32 samples_left;
/* Mixing volume */
uint volume_left;
uint volume_right;
uint flags;
};
static MixerChannel _channels[8];
static uint32 _play_rate;
static void mix_int8_to_int16(MixerChannel *sc, int16 *buffer, uint samples)
{
int8 *b;
uint32 frac_pos;
uint32 frac_speed;
uint volume_left;
uint volume_right;
if (samples > sc->samples_left) samples = sc->samples_left;
sc->samples_left -= samples;
assert(samples > 0);
b = sc->memory + sc->pos;
frac_pos = sc->frac_pos;
frac_speed = sc->frac_speed;
volume_left = sc->volume_left;
volume_right = sc->volume_right;
if (frac_speed == 0x10000) {
/* Special case when frac_speed is 0x10000 */
do {
buffer[0] += *b * volume_left >> 8;
buffer[1] += *b * volume_right >> 8;
b++;
buffer += 2;
} while (--samples > 0);
} else {
do {
buffer[0] += *b * volume_left >> 8;
buffer[1] += *b * volume_right >> 8;
buffer += 2;
frac_pos += frac_speed;
b += frac_pos >> 16;
frac_pos &= 0xffff;
} while (--samples > 0);
}
sc->frac_pos = frac_pos;
sc->pos = b - sc->memory;
}
static void MxCloseChannel(MixerChannel *mc)
{
if (mc->flags & MX_AUTOFREE) free(mc->memory);
mc->active = false;
mc->memory = NULL;
}
void MxMixSamples(void *buffer, uint samples)
{
MixerChannel *mc;
/* Clear the buffer */
memset(buffer, 0, sizeof(int16) * 2 * samples);
/* Mix each channel */
for (mc = _channels; mc != endof(_channels); mc++) {
if (mc->active) {
mix_int8_to_int16(mc, (int16*)buffer, samples);
if (mc->samples_left == 0) MxCloseChannel(mc);
}
}
}
MixerChannel *MxAllocateChannel()
{
MixerChannel *mc;
for (mc = _channels; mc != endof(_channels); mc++)
if (mc->memory == NULL) {
mc->active = false;
return mc;
}
return NULL;
}
void MxSetChannelRawSrc(MixerChannel *mc, int8 *mem, uint size, uint rate, uint flags)
{
mc->memory = mem;
mc->flags = flags;
mc->frac_pos = 0;
mc->pos = 0;
mc->frac_speed = (rate << 16) / _play_rate;
/* adjust the magnitude to prevent overflow */
while (size & 0xFFFF0000) {
size >>= 1;
rate = (rate >> 1) + 1;
}
mc->samples_left = size * _play_rate / rate;
}
void MxSetChannelVolume(MixerChannel *mc, uint left, uint right)
{
mc->volume_left = left;
mc->volume_right = right;
}
void MxActivateChannel(MixerChannel* mc)
{
mc->active = true;
}
bool MxInitialize(uint rate)
{
_play_rate = rate;
return true;
}
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