📄 sloader.c
字号:
/* MikMod sound library
(c) 1998, 1999, 2000, 2001 Miodrag Vallat and others - see file AUTHORS
for complete list.
This library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library 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 Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.
*/
/*==============================================================================
$Id: sloader.c,v 1.1.1.1 2004/01/21 01:36:35 raph Exp $
Routines for loading samples. The sample loader utilizes the routines
provided by the "registered" sample loader.
==============================================================================*/
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include "mikmod_internals.h"
static int sl_rlength;
static SWORD sl_old;
static SWORD *sl_buffer=NULL;
static SAMPLOAD *musiclist=NULL,*sndfxlist=NULL;
/* size of the loader buffer in words */
#define SLBUFSIZE 2048
/* IT-Compressed status structure */
typedef struct ITPACK {
UWORD bits; /* current number of bits */
UWORD bufbits; /* bits in buffer */
SWORD last; /* last output */
UBYTE buf; /* bit buffer */
} ITPACK;
BOOL SL_Init(SAMPLOAD* s)
{
if(!sl_buffer)
if(!(sl_buffer=_mm_malloc(SLBUFSIZE*sizeof(SWORD)))) return 0;
sl_rlength = s->length;
if(s->infmt & SF_16BITS) sl_rlength>>=1;
sl_old = 0;
return 1;
}
void SL_Exit(SAMPLOAD *s)
{
if(sl_rlength>0) _mm_fseek(s->reader,sl_rlength,SEEK_CUR);
if(sl_buffer) {
free(sl_buffer);
sl_buffer=NULL;
}
}
/* unpack a 8bit IT packed sample */
static BOOL read_itcompr8(ITPACK* status,MREADER *reader,SWORD *sl_buffer,UWORD count,UWORD* incnt)
{
SWORD *dest=sl_buffer,*end=sl_buffer+count;
UWORD x,y,needbits,havebits,new_count=0;
UWORD bits = status->bits;
UWORD bufbits = status->bufbits;
SBYTE last = status->last;
UBYTE buf = status->buf;
while (dest<end) {
needbits=new_count?3:bits;
x=havebits=0;
while (needbits) {
/* feed buffer */
if (!bufbits) {
if((*incnt)--)
buf=_mm_read_UBYTE(reader);
else
buf=0;
bufbits=8;
}
/* get as many bits as necessary */
y = needbits<bufbits?needbits:bufbits;
x|= (buf & ((1<<y)- 1))<<havebits;
buf>>=y;
bufbits-=y;
needbits-=y;
havebits+=y;
}
if (new_count) {
new_count = 0;
if (++x >= bits)
x++;
bits = x;
continue;
}
if (bits<7) {
if (x==(1<<(bits-1))) {
new_count = 1;
continue;
}
}
else if (bits<9) {
y = (0xff >> (9-bits)) - 4;
if ((x>y)&&(x<=y+8)) {
if ((x-=y)>=bits)
x++;
bits = x;
continue;
}
}
else if (bits<10) {
if (x>=0x100) {
bits=x-0x100+1;
continue;
}
} else {
/* error in compressed data... */
_mm_errno=MMERR_ITPACK_INVALID_DATA;
return 0;
}
if (bits<8) /* extend sign */
x = ((SBYTE)(x <<(8-bits))) >> (8-bits);
*(dest++)= (last+=x) << 8; /* convert to 16 bit */
}
status->bits = bits;
status->bufbits = bufbits;
status->last = last;
status->buf = buf;
return dest-sl_buffer;
}
/* unpack a 16bit IT packed sample */
static BOOL read_itcompr16(ITPACK *status,MREADER *reader,SWORD *sl_buffer,UWORD count,UWORD* incnt)
{
SWORD *dest=sl_buffer,*end=sl_buffer+count;
SLONG x,y,needbits,havebits,new_count=0;
UWORD bits = status->bits;
UWORD bufbits = status->bufbits;
SWORD last = status->last;
UBYTE buf = status->buf;
while (dest<end) {
needbits=new_count?4:bits;
x=havebits=0;
while (needbits) {
/* feed buffer */
if (!bufbits) {
if((*incnt)--)
buf=_mm_read_UBYTE(reader);
else
buf=0;
bufbits=8;
}
/* get as many bits as necessary */
y=needbits<bufbits?needbits:bufbits;
x|=(buf &((1<<y)-1))<<havebits;
buf>>=y;
bufbits-=y;
needbits-=y;
havebits+=y;
}
if (new_count) {
new_count = 0;
if (++x >= bits)
x++;
bits = x;
continue;
}
if (bits<7) {
if (x==(1<<(bits-1))) {
new_count=1;
continue;
}
}
else if (bits<17) {
y=(0xffff>>(17-bits))-8;
if ((x>y)&&(x<=y+16)) {
if ((x-=y)>=bits)
x++;
bits = x;
continue;
}
}
else if (bits<18) {
if (x>=0x10000) {
bits=x-0x10000+1;
continue;
}
} else {
/* error in compressed data... */
_mm_errno=MMERR_ITPACK_INVALID_DATA;
return 0;
}
if (bits<16) /* extend sign */
x = ((SWORD)(x<<(16-bits)))>>(16-bits);
*(dest++)=(last+=x);
}
status->bits = bits;
status->bufbits = bufbits;
status->last = last;
status->buf = buf;
return dest-sl_buffer;
}
static BOOL SL_LoadInternal(void* buffer,UWORD infmt,UWORD outfmt,int scalefactor,ULONG length,MREADER* reader,BOOL dither)
{
SBYTE *bptr = (SBYTE*)buffer;
SWORD *wptr = (SWORD*)buffer;
int stodo,t,u;
int result,c_block=0; /* compression bytes until next block */
ITPACK status;
UWORD incnt;
while(length) {
stodo=(length<SLBUFSIZE)?length:SLBUFSIZE;
if(infmt&SF_ITPACKED) {
sl_rlength=0;
if (!c_block) {
status.bits = (infmt & SF_16BITS) ? 17 : 9;
status.last = status.bufbits = 0;
incnt=_mm_read_I_UWORD(reader);
c_block = (infmt & SF_16BITS) ? 0x4000 : 0x8000;
if(infmt&SF_DELTA) sl_old=0;
}
if (infmt & SF_16BITS) {
if(!(result=read_itcompr16(&status,reader,sl_buffer,stodo,&incnt)))
return 1;
} else {
if(!(result=read_itcompr8(&status,reader,sl_buffer,stodo,&incnt)))
return 1;
}
if(result!=stodo) {
_mm_errno=MMERR_ITPACK_INVALID_DATA;
return 1;
}
c_block -= stodo;
} else {
if(infmt&SF_16BITS) {
if(infmt&SF_BIG_ENDIAN)
_mm_read_M_SWORDS(sl_buffer,stodo,reader);
else
_mm_read_I_SWORDS(sl_buffer,stodo,reader);
} else {
SBYTE *src;
SWORD *dest;
reader->Read(reader,sl_buffer,sizeof(SBYTE)*stodo);
src = (SBYTE*)sl_buffer;
dest = sl_buffer;
src += stodo;dest += stodo;
for(t=0;t<stodo;t++) {
src--;dest--;
*dest = (*src)<<8;
}
}
sl_rlength-=stodo;
}
if(infmt & SF_DELTA)
for(t=0;t<stodo;t++) {
sl_buffer[t] += sl_old;
sl_old = sl_buffer[t];
}
if((infmt^outfmt) & SF_SIGNED)
for(t=0;t<stodo;t++)
sl_buffer[t]^= 0x8000;
if(scalefactor) {
int idx = 0;
SLONG scaleval;
/* Sample Scaling... average values for better results. */
t= 0;
while(t<stodo && length) {
scaleval = 0;
for(u=scalefactor;u && t<stodo;u--,t++)
scaleval+=sl_buffer[t];
sl_buffer[idx++]=scaleval/(scalefactor-u);
length--;
}
stodo = idx;
} else
length -= stodo;
if (dither) {
if((infmt & SF_STEREO) && !(outfmt & SF_STEREO)) {
/* dither stereo to mono, average together every two samples */
SLONG avgval;
int idx = 0;
t=0;
while(t<stodo && length) {
avgval=sl_buffer[t++];
avgval+=sl_buffer[t++];
sl_buffer[idx++]=avgval>>1;
length-=2;
}
stodo = idx;
}
}
if(outfmt & SF_16BITS) {
for(t=0;t<stodo;t++)
*(wptr++)=sl_buffer[t];
} else {
for(t=0;t<stodo;t++)
*(bptr++)=sl_buffer[t]>>8;
}
}
return 0;
}
BOOL SL_Load(void* buffer,SAMPLOAD *smp,ULONG length)
{
return SL_LoadInternal(buffer,smp->infmt,smp->outfmt,smp->scalefactor,
length,smp->reader,0);
}
/* Registers a sample for loading when SL_LoadSamples() is called. */
SAMPLOAD* SL_RegisterSample(SAMPLE* s,int type,MREADER* reader)
{
SAMPLOAD *news,**samplist,*cruise;
if(type==MD_MUSIC) {
samplist = &musiclist;
cruise = musiclist;
} else
if (type==MD_SNDFX) {
samplist = &sndfxlist;
cruise = sndfxlist;
} else
return NULL;
/* Allocate and add structure to the END of the list */
if(!(news=(SAMPLOAD*)_mm_malloc(sizeof(SAMPLOAD)))) return NULL;
if(cruise) {
while(cruise->next) cruise=cruise->next;
cruise->next = news;
} else
*samplist = news;
news->infmt = s->flags & SF_FORMATMASK;
news->outfmt = news->infmt;
news->reader = reader;
news->sample = s;
news->length = s->length;
news->loopstart = s->loopstart;
news->loopend = s->loopend;
return news;
}
static void FreeSampleList(SAMPLOAD* s)
{
SAMPLOAD *old;
while(s) {
old = s;
s = s->next;
free(old);
}
}
/* Returns the total amount of memory required by the samplelist queue. */
static ULONG SampleTotal(SAMPLOAD* samplist,int type)
{
int total = 0;
while(samplist) {
samplist->sample->flags=
(samplist->sample->flags&~SF_FORMATMASK)|samplist->outfmt;
total += MD_SampleLength(type,samplist->sample);
samplist=samplist->next;
}
return total;
}
static ULONG RealSpeed(SAMPLOAD *s)
{
return(s->sample->speed/(s->scalefactor?s->scalefactor:1));
}
static BOOL DitherSamples(SAMPLOAD* samplist,int type)
{
SAMPLOAD *c2smp=NULL;
ULONG maxsize, speed;
SAMPLOAD *s;
if(!samplist) return 0;
if((maxsize=MD_SampleSpace(type)*1024))
while(SampleTotal(samplist,type)>maxsize) {
/* First Pass - check for any 16 bit samples */
s = samplist;
while(s) {
if(s->outfmt & SF_16BITS) {
SL_Sample16to8(s);
break;
}
s=s->next;
}
/* Second pass (if no 16bits found above) is to take the sample with
the highest speed and dither it by half. */
if(!s) {
s = samplist;
speed = 0;
while(s) {
if((s->sample->length) && (RealSpeed(s)>speed)) {
speed=RealSpeed(s);
c2smp=s;
}
s=s->next;
}
if (c2smp)
SL_HalveSample(c2smp,2);
}
}
/* Samples dithered, now load them ! */
s = samplist;
while(s) {
/* sample has to be loaded ? -> increase number of samples, allocate
memory and load sample. */
if(s->sample->length) {
if(s->sample->seekpos)
_mm_fseek(s->reader, s->sample->seekpos, SEEK_SET);
/* Call the sample load routine of the driver module. It has to
return a 'handle' (>=0) that identifies the sample. */
s->sample->handle = MD_SampleLoad(s, type);
s->sample->flags = (s->sample->flags & ~SF_FORMATMASK) | s->outfmt;
if(s->sample->handle<0) {
FreeSampleList(samplist);
if(_mm_errorhandler) _mm_errorhandler();
return 1;
}
}
s = s->next;
}
FreeSampleList(samplist);
return 0;
}
BOOL SL_LoadSamples(void)
{
BOOL ok;
_mm_critical = 0;
if((!musiclist)&&(!sndfxlist)) return 0;
ok=DitherSamples(musiclist,MD_MUSIC)||DitherSamples(sndfxlist,MD_SNDFX);
musiclist=sndfxlist=NULL;
return ok;
}
void SL_Sample16to8(SAMPLOAD* s)
{
s->outfmt &= ~SF_16BITS;
s->sample->flags = (s->sample->flags&~SF_FORMATMASK) | s->outfmt;
}
void SL_Sample8to16(SAMPLOAD* s)
{
s->outfmt |= SF_16BITS;
s->sample->flags = (s->sample->flags&~SF_FORMATMASK) | s->outfmt;
}
void SL_SampleSigned(SAMPLOAD* s)
{
s->outfmt |= SF_SIGNED;
s->sample->flags = (s->sample->flags&~SF_FORMATMASK) | s->outfmt;
}
void SL_SampleUnsigned(SAMPLOAD* s)
{
s->outfmt &= ~SF_SIGNED;
s->sample->flags = (s->sample->flags&~SF_FORMATMASK) | s->outfmt;
}
void SL_HalveSample(SAMPLOAD* s,int factor)
{
s->scalefactor=factor>0?factor:2;
s->sample->divfactor = s->scalefactor;
s->sample->length = s->length / s->scalefactor;
s->sample->loopstart = s->loopstart / s->scalefactor;
s->sample->loopend = s->loopend / s->scalefactor;
}
/* ex:set ts=4: */
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -