id3.c

ESS3890+SL原代码（1*16内存）

/* Copyright 1997, ESS Technology, Inc.					*/
/* SCCSID @(#)id3.c	4.1 11/05/02 */

/*
 * $Log$ 
 */

#ifdef ID3
#include "common.h"
#include "memmap.h"
#include "buffer.h"
#include "id3.h"

/************************************************************************
  Function: Getting ID3 information and skip ID3-V2.x data at beginning
	of MP3 files.
  Description: Since most of VCD3.0 targets are low on DRAM and/or ROM 
	space, we have an option to enable "USE_ID3_INFO". 
*************************************************************************/

/**************************************************************************
 * global variables 
 **************************************************************************/
int ID3_ABV_offset = 0;
#ifdef USE_ID3_INFO
ID3_INFO *ID3_info;
#endif USE_ID3_INFO


/**************************************************************************
 *local variables 
 **************************************************************************/
#ifdef USE_ID3_INFO
static struct {
    char *name[3];
    char *artist[3];
    char *album[3];
    char *year[3];
    char *content[3];
} frame_id
= {{"TT2","TIT2","TIT2"}, {"TP1","TPE1","TPE1"}, {"TAL","TALB","TALB"}, 
{"TYE","TYER", "TYER"}, {"TCO","TCON","TCON"}};
#endif USE_ID3_INFO


/**************************************************************************
 *local functions
 **************************************************************************/
#ifdef USE_ID3_INFO
static int frame_id_match(char *, int);
static int get_frame_size(char *, int);
#endif USE_ID3_INFO
static int get_tag_size(char *);


#ifdef USE_ID3_INFO
static int frame_id_match(char *s, int version)
{
    int id=0, len=4, k=version-2;
    if (version==2) len = 3;
    if (strncmp(s, frame_id.name[k], len) == 0) {
        id = 1;
    } else if (strncmp(s, frame_id.artist[k], len) == 0) {
        id = 2;
    } else if (strncmp(s, frame_id.album[k], len) == 0) {
        id = 3;
    } else if (strncmp(s, frame_id.year[k], len) == 0) {
        id = 4;
    } else if (strncmp(s, frame_id.content[k], len) == 0) {
        id = 5;
    }
    if (s[0]==0&&s[1]==0&&s[2]==0) id=-1; 
    return id;
}

static int get_frame_size(char *s, int version)
{
    int size = ((s[0]&0x7f)<<14)+((s[1]&0x7f)<<7)+(s[2]&0x7f);
    if (version>2) size=(size<<7)+(s[3]&0x7f);
    return size;
}
#endif USE_ID3_INFO

static int get_tag_size(char *s)
{
    int size = ((s[0]&0x7f)<<21)+((s[1]&0x7f)<<14)+((s[2]&0x7f)<<7)+
                (s[3]&0x7f);

    return (size);
}

int ID3_detect(int start, int end, int sec_size)
{
    char *p, *s, *info[6];
    int i=0, k, id, offset, sector, version, tag_size=0, len, min, lang=0;
    int size, factor, header_size=10;



#ifdef USE_ID3_INFO
    ID3_info = (ID3_INFO *) dram_cached(ABV_end);
    p = (unsigned char *)ID3_info;
    info[0] = p+3;
    info[1] = info[0]+ MAX_ID3_STRING;
    info[2] = info[1] + MAX_ID3_STRING;
    info[3] = info[2] + MAX_ID3_STRING;
    info[4] = info[3] + 4;
    for(i=0; i<2407; i++) p[i] = 0;
    for(i=0; i<2; i++){
        ID3_info->str_len[i] = 0;
        ID3_info->position[i] = 0;
    }
    id3_str_index = 0;
    ID3_info->cur_timer = 0;
    ID3_info->cur_track = -1;

#endif USE_ID3_INFO

    /* get ID3 data */
    sector = start;
    if (getSectors(start,1,2048) != 1) return 0;
    s = (char *)dram(GETSECTOR_DATA_START);
    if (strncmp(s, "ID3", 3) == 0) { /* ID3 V2.x */
#ifdef USE_ID3_INFO
	p[0] = 'I'; p[1] = version = s[3]; p[2] = s[4]; 
#endif 

        tag_size = get_tag_size(s+6);
	if (s[5]&0x10) header_size = 20; /* header+footer */
	tag_size += header_size; 

#ifdef USE_ID3_INFO
        s+=header_size;
	i = header_size;
	offset = sec_size;
	while (i < tag_size){
            id = frame_id_match(s, version);
            if (id<0) break;
	    len=(version>2)?4:3;
            s+=len; i+=len;
            size = get_frame_size(s, version);
            len=(version>2)?6:3;
            s+=len; i+=len;
            if (id) {
		/* For Text information frames the first byte 
		 * describes text encoding type...
		 *     0x00: ascii (ISO-8859-1)
		 *     0x01: Unicode (ISO/IEC 10646-1:1993, UCS-2)
		 * 
		 * NOTE: we don't really handle Unicode data(16bits)..
		 * we are just copying the lower bytes, in case they 
		 * are ascii characters.
		 */
		factor = (*s) ? 2 : 1;
                /*Just for now, we didn't handle DBCC*/
                if(factor == 2) return 0;
		min = (size > MAX_ID3_STRING*factor) ?
		    (MAX_ID3_STRING*factor) : size;		
		
		/* adjust for 1st byte */ 
                p = s+factor; min--; 
		id--; /* index of ID3 text buffer */ 
		if (*p) lang++;		

                for (k=0; k<min; k+=factor) 
		    *info[id]++ = p[k];
            }

	    if (lang >= MAX_ID3_ITEMS) break;

            s+=size; i+=size;
            if (i >= offset) {
                sector = adjCDtime(sector, 1, 1);
                if (getSectors(sector, 1, 2048)!=1)
                    return 0;

		s = (char *)dram(GETSECTOR_DATA_START);
		offset += sec_size;
            }
        } 

        if (!lang) return (tag_size);

	/* no such case for ID3 
	if (size<128) return 0;*/
#endif USE_ID3_INFO
    } else { /* ID3 V1.x */
	tag_size = 0; /* for prepended ID3 tags only */
	
#ifdef USE_ID3_INFO
	/* ID3 is in the last 2 sectors of MP3 file (last 128 Bytes) */
	end = adjCDtime(end, 2, -1);	
	if(getSectors(end,2, 2048) != 1) return 0;

	/* Find "TAG" starting from end of file */
	s = (char *)dram(GETSECTOR_DATA_START + 1024); /* point to end */
	for(i=MAX_ID3V1_SEARCH;i>0;i--,s--) 
	{   
	    if (*s == 'T') {
		if (strncmp(s, "TAG", 3) == 0) { 
		    
#if 0
		    /* we found ID3V1 info */
                    p = (unsigned char *) ID3_info;
		    for(i = 0; i < 127; i++) *p++ = *s++;
#else
                    for(i=0; i<3; i++) ID3_info->TAG[i] = *s++;
                    for(i=0; i<30; i++) ID3_info->song_title[i] = *s++;
                    for(i=0; i<30; i++) ID3_info->artist[i] = *s++;
                    for(i=0; i<30; i++) ID3_info->album[i] = *s++;
                    for(i=0; i<4; i++) ID3_info->year[i] = *s++;
                    for(i=0; i<30; i++) ID3_info->type[i] = *s++;
#endif

		    return (0); /* success */
		}
	    }
    	}
	
#endif USE_ID3_INFO
    }

    return (tag_size); 
}
#endif ID3