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Diffstat (limited to 'src/pcsound/pcsound_sdl.c')
| -rw-r--r-- | src/pcsound/pcsound_sdl.c | 179 |
1 files changed, 0 insertions, 179 deletions
diff --git a/src/pcsound/pcsound_sdl.c b/src/pcsound/pcsound_sdl.c deleted file mode 100644 index 50820394..00000000 --- a/src/pcsound/pcsound_sdl.c +++ /dev/null @@ -1,179 +0,0 @@ -// Emacs style mode select -*- C++ -*- -//----------------------------------------------------------------------------- -// -// Copyright(C) 2007 Simon Howard -// -// This program is free software; you can redistribute it and/or -// modify it under the terms of the GNU General Public License -// as published by the Free Software Foundation; either version 2 -// of the License, or (at your option) any later version. -// -// This program is distributed in the hope that it will be useful, -// but WITHOUT ANY WARRANTY; without even the implied warranty of -// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -// GNU General Public License for more details. -// -// You should have received a copy of the GNU General Public License -// along with this program; if not, write to the Free Software -// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA -// 02111-1307, USA. -// -// DESCRIPTION: -// PC speaker interface. -// -//----------------------------------------------------------------------------- - -#include <stdio.h> -#include <stdlib.h> - -#include "SDL.h" -#include "SDL_mixer.h" - -#include "pcsound.h" - -#define SQUARE_WAVE_AMP 0x2000 - -static pcsound_callback_func callback; - -// Output sound format - -static int mixing_freq; -static Uint16 mixing_format; -static int mixing_channels; - -// Currently playing sound -// current_remaining is the number of remaining samples that must be played -// before we invoke the callback to get the next frequency. - -static int current_remaining; -static int current_freq; - -static int phase_offset = 0; - -// Mixer function that does the PC speaker emulation - -static void PCSound_Mix_Callback(void *udata, Uint8 *stream, int len) -{ - Sint16 *leftptr; - Sint16 *rightptr; - Sint16 this_value; - int oldfreq; - int i; - int nsamples; - - // Number of samples is quadrupled, because of 16-bit and stereo - - nsamples = len / 4; - - leftptr = (Sint16 *) stream; - rightptr = ((Sint16 *) stream) + 1; - - // Fill the output buffer - - for (i=0; i<nsamples; ++i) - { - // Has this sound expired? If so, invoke the callback to get - // the next frequency. - - while (current_remaining == 0) - { - oldfreq = current_freq; - - // Get the next frequency to play - - callback(¤t_remaining, ¤t_freq); - - if (current_freq != 0) - { - // Adjust phase to match to the new frequency. - // This gives us a smooth transition between different tones, - // with no impulse changes. - - phase_offset = (phase_offset * oldfreq) / current_freq; - } - - current_remaining = (current_remaining * mixing_freq) / 1000; - } - - // Set the value for this sample. - - if (current_freq == 0) - { - // Silence - - this_value = 0; - } - else - { - int frac; - - // Determine whether we are at a peak or trough in the current - // sound. Multiply by 2 so that frac % 2 will give 0 or 1 - // depending on whether we are at a peak or trough. - - frac = (phase_offset * current_freq * 2) / mixing_freq; - - if ((frac % 2) == 0) - { - this_value = SQUARE_WAVE_AMP; - } - else - { - this_value = -SQUARE_WAVE_AMP; - } - - ++phase_offset; - } - - --current_remaining; - - // Use the same value for the left and right channels. - - *leftptr += this_value; - *rightptr += this_value; - - leftptr += 2; - rightptr += 2; - } -} - -static int PCSound_SDL_Init(pcsound_callback_func callback_func) -{ - // Check that SDL_mixer has been opened already - // If not, fail - - if (!Mix_QuerySpec(&mixing_freq, &mixing_format, &mixing_channels)) - { - return 0; - } - - // Only supports AUDIO_S16SYS - - if (mixing_format != AUDIO_S16SYS || mixing_channels != 2) - { - fprintf(stderr, - "PCSound_SDL only supports native signed 16-bit LSB, " - "stereo format!\n"); - return 0; - } - - callback = callback_func; - current_freq = 0; - current_remaining = 0; - - Mix_SetPostMix(PCSound_Mix_Callback, NULL); - - return 1; -} - -static void PCSound_SDL_Shutdown(void) -{ -} - -pcsound_driver_t pcsound_sdl_driver = -{ - "SDL", - PCSound_SDL_Init, - PCSound_SDL_Shutdown, -}; - |