mirror of
https://github.com/kichikuou/xsystem35-sdl2.git
synced 2026-09-28 17:58:09 +03:00
71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
/*
|
|
* shpcmlib.c ShSound用 pcmlib
|
|
*
|
|
* Copyright (C) 1997-1998 Masaki Chikama (Wren) <chikama@kasumi.ipl.mech.nagoya-u.ac.jp>
|
|
* 1998- <masaki-c@is.aist-nara.ac.jp>
|
|
*
|
|
* 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
|
|
*
|
|
*/
|
|
/* $Id: shpcmlib.c,v 1.2 2003/08/02 13:10:32 chikama Exp $ */
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <limits.h>
|
|
#include <SDL_mixer.h>
|
|
|
|
#include "portab.h"
|
|
|
|
/*
|
|
左右のチャンネルの入れ換え
|
|
*/
|
|
void pcmlib_reverse_pan_memory(Mix_Chunk *chunk) {
|
|
if (chunk == NULL) return;
|
|
|
|
short *buf = (short*)chunk->abuf;
|
|
int len = chunk->alen / 4;
|
|
for (int i = 0; i < len; i++) {
|
|
short tmp = buf[0];
|
|
buf[0] = buf[1];
|
|
buf[1] = tmp;
|
|
buf += 2;
|
|
}
|
|
}
|
|
|
|
/*
|
|
メモリ上の PCM データにフェード効果をかける
|
|
*/
|
|
void pcmlib_fade_volume_memory(Mix_Chunk *chunk, int start, int range) {
|
|
if (chunk == NULL) return;
|
|
|
|
start *= 441; // 10ms -> sample
|
|
range *= 441; // 10ms -> sample
|
|
|
|
if (chunk->alen / 4 < start + range)
|
|
return;
|
|
|
|
short *buf = (short*)chunk->abuf;
|
|
buf += start * 2;
|
|
|
|
// 指定の場所から徐々に音量を下げる
|
|
for (int i = range; i > 0; i--) {
|
|
buf[0] = buf[0] * i / range;
|
|
buf[1] = buf[1] * i / range;
|
|
buf += 2;
|
|
}
|
|
|
|
// 残りは無音
|
|
memset(buf, 0, chunk->abuf + chunk->alen - (Uint8*)buf);
|
|
}
|