diff options
author | rubidium <rubidium@openttd.org> | 2007-01-02 19:19:48 +0000 |
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committer | rubidium <rubidium@openttd.org> | 2007-01-02 19:19:48 +0000 |
commit | 66bbf336c6af7353ef0aeed58002c46543b30635 (patch) | |
tree | ad4a63860df2626b22f77e7dac712e958bea54cb /src/mixer.c | |
parent | ccc0a3f4dbf58c005b22341ac8874252924690cd (diff) | |
download | openttd-66bbf336c6af7353ef0aeed58002c46543b30635.tar.xz |
(svn r7759) -Merge: makefile rewrite. This merge features:
- A proper ./configure, so everything needs to be configured only once, not for every make.
- Usage of makedepend when available. This greatly reduces the time needed for generating the dependencies.
- A generator for all project files. There is a single file with sources, which is used to generate Makefiles and the project files for MSVC.
- Proper support for OSX universal binaries.
- Object files for non-MSVC compiles are also placed in separate directories, making is faster to switch between debug and release compiles and it does not touch the directory with the source files.
- Functionality to make a bundle of all needed files for for example a nightly or distribution of a binary with all needed GRFs and language files.
Note: as this merge moves almost all files, it is recommended to make a backup of your working copy before updating your working copy.
Diffstat (limited to 'src/mixer.c')
-rw-r--r-- | src/mixer.c | 140 |
1 files changed, 140 insertions, 0 deletions
diff --git a/src/mixer.c b/src/mixer.c new file mode 100644 index 000000000..5b97afbf9 --- /dev/null +++ b/src/mixer.c @@ -0,0 +1,140 @@ +/* $Id$ */ + +#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, buffer, samples); + if (mc->samples_left == 0) MxCloseChannel(mc); + } + } +} + +MixerChannel *MxAllocateChannel(void) +{ + 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; +} |