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-rw-r--r--setedit/mp3/libamp/getbits.c274
1 files changed, 274 insertions, 0 deletions
diff --git a/setedit/mp3/libamp/getbits.c b/setedit/mp3/libamp/getbits.c
new file mode 100644
index 0000000..6a1577e
--- /dev/null
+++ b/setedit/mp3/libamp/getbits.c
@@ -0,0 +1,274 @@
+/* this file is a part of amp software, (C) tomislav uzelac 1996,1997
+*/
+
+/* getbits.c bit level routines, input buffer
+ *
+ * Created by: tomislav uzelac Apr 1996
+ * better synchronization, tomislav uzelac, Apr 23 1997
+ */
+#include "amp.h"
+#include "audio.h"
+#include "formats.h"
+#include "rtbuf.h"
+
+#define GETBITS
+#include "getbits.h"
+
+/*
+ * buffer and bit manipulation functions ***************************************
+ */
+static inline int _fillbfr(unsigned int size)
+{
+ _bptr=0;
+ return get_input(_buffer, size);
+}
+
+static inline int readsync()
+{
+ _bptr=0;
+ _buffer[0]=_buffer[1];
+ _buffer[1]=_buffer[2];
+ _buffer[2]=_buffer[3];
+ return get_input(&_buffer[3],1);
+}
+
+static inline unsigned int _getbits(int n)
+{
+unsigned int pos,ret_value;
+
+ pos = _bptr >> 3;
+ ret_value = _buffer[pos] << 24 |
+ _buffer[pos+1] << 16 |
+ _buffer[pos+2] << 8 |
+ _buffer[pos+3];
+ ret_value <<= _bptr & 7;
+ ret_value >>= 32 - n;
+ _bptr += n;
+ return ret_value;
+}
+
+int fillbfr(unsigned int advance)
+{
+int overflow,retval;
+
+ retval=get_input(&buffer[append], advance);
+
+ if ( append + advance >= BUFFER_SIZE ) {
+ overflow = append + advance - BUFFER_SIZE;
+ memcpy (buffer,&buffer[BUFFER_SIZE], overflow);
+ if (overflow < 4) memcpy(&buffer[BUFFER_SIZE],buffer,4);
+ append = overflow;
+ } else {
+ if (append==0) memcpy(&buffer[BUFFER_SIZE],buffer,4);
+ append+=advance;
+ }
+ return retval;
+}
+
+unsigned int getbits(int n)
+{
+ if (n) {
+ unsigned int pos,ret_value;
+
+ pos = data >> 3;
+ ret_value = buffer[pos] << 24 |
+ buffer[pos+1] << 16 |
+ buffer[pos+2] << 8 |
+ buffer[pos+3];
+ ret_value <<= data & 7;
+ ret_value >>= 32 - n;
+
+ data += n;
+ data &= (8*BUFFER_SIZE)-1;
+
+ return ret_value;
+ } else
+ return 0;
+}
+
+/*
+ * header and side info parsing stuff ******************************************
+ */
+static inline void parse_header(struct AUDIO_HEADER *header)
+{
+ header->ID=_getbits(1);
+ header->layer=_getbits(2);
+ header->protection_bit=_getbits(1);
+ header->bitrate_index=_getbits(4);
+ header->sampling_frequency=_getbits(2);
+ header->padding_bit=_getbits(1);
+ header->private_bit=_getbits(1);
+ header->mode=_getbits(2);
+ header->mode_extension=_getbits(2);
+ if (!header->mode) header->mode_extension=0;
+ header->copyright=_getbits(1);
+ header->original=_getbits(1);
+ header->emphasis=_getbits(2);
+}
+
+static inline int header_sanity_check(struct AUDIO_HEADER *header)
+{
+ if ( header->layer==0 ||
+ header->bitrate_index==15 ||
+ header->sampling_frequency==3) return -1;
+
+ /* an additional check to make shure that stuffing never gets mistaken
+ * for a syncword. This rules out some legal layer1 streams, but who
+ * cares about layer1 anyway :-). I must get this right sometime.
+ */
+ if ( header->ID==1 && header->layer==3 && header->protection_bit==1) return -1;
+ return 0;
+}
+
+
+int gethdr(struct AUDIO_HEADER *header)
+{
+int s,retval;
+struct AUDIO_HEADER tmp;
+
+ /* TODO: add a simple byte counter to check only first, say, 1024
+ * bytes for a new header and then return GETHDR_SYN
+ */
+ if ((retval=_fillbfr(4))!=0) return retval;
+
+ for(;;) {
+ while ((s=_getbits(12)) != 0xfff) {
+ if (s==0xffe) {
+ parse_header(&tmp);
+ if (header_sanity_check(&tmp)==0) return GETHDR_NS;
+ }
+ if ((retval=readsync())!=0) return retval;
+ }
+
+ parse_header(&tmp);
+ if (header_sanity_check(&tmp)!=0) {
+ if ((retval=readsync())!=0) return retval;
+ } else break;
+ }
+
+ if (tmp.layer==3) return GETHDR_FL1;
+ /* if (tmp.layer==2) return GETHDR_FL2; */
+ if (tmp.bitrate_index==0) return GETHDR_FF;
+
+ memcpy(header,&tmp,sizeof(tmp));
+ return 0;
+}
+
+/* dummy function, to get crc out of the way
+*/
+void getcrc()
+{
+ _fillbfr(2);
+ _getbits(16);
+}
+
+/* sizes of side_info:
+ * MPEG1 1ch 17 2ch 32
+ * MPEG2 1ch 9 2ch 17
+ */
+void getinfo(struct AUDIO_HEADER *header,struct SIDE_INFO *info)
+{
+int gr,ch,scfsi_band,region,window;
+int nch;
+ if (header->mode==3) {
+ nch=1;
+ if (header->ID) {
+ _fillbfr(17);
+ info->main_data_begin=_getbits(9);
+ _getbits(5);
+ } else {
+ _fillbfr(9);
+ info->main_data_begin=_getbits(8);
+ _getbits(1);
+ }
+ } else {
+ nch=2;
+ if (header->ID) {
+ _fillbfr(32);
+ info->main_data_begin=_getbits(9);
+ _getbits(3);
+ } else {
+ _fillbfr(17);
+ info->main_data_begin=_getbits(8);
+ _getbits(2);
+ }
+ }
+
+ if (header->ID) for (ch=0;ch<nch;ch++)
+ for (scfsi_band=0;scfsi_band<4;scfsi_band++)
+ info->scfsi[ch][scfsi_band]=_getbits(1);
+
+ for (gr=0;gr<(header->ID ? 2:1);gr++)
+ for (ch=0;ch<nch;ch++) {
+ info->part2_3_length[gr][ch]=_getbits(12);
+ info->big_values[gr][ch]=_getbits(9);
+ info->global_gain[gr][ch]=_getbits(8);
+ if (header->ID) info->scalefac_compress[gr][ch]=_getbits(4);
+ else info->scalefac_compress[gr][ch]=_getbits(9);
+ info->window_switching_flag[gr][ch]=_getbits(1);
+
+ if (info->window_switching_flag[gr][ch]) {
+ info->block_type[gr][ch]=_getbits(2);
+ info->mixed_block_flag[gr][ch]=_getbits(1);
+
+ for (region=0;region<2;region++)
+ info->table_select[gr][ch][region]=_getbits(5);
+ info->table_select[gr][ch][2]=0;
+
+ for (window=0;window<3;window++)
+ info->subblock_gain[gr][ch][window]=_getbits(3);
+ } else {
+ for (region=0;region<3;region++)
+ info->table_select[gr][ch][region]=_getbits(5);
+
+ info->region0_count[gr][ch]=_getbits(4);
+ info->region1_count[gr][ch]=_getbits(3);
+ info->block_type[gr][ch]=0;
+ }
+
+ if (header->ID) info->preflag[gr][ch]=_getbits(1);
+ info->scalefac_scale[gr][ch]=_getbits(1);
+ info->count1table_select[gr][ch]=_getbits(1);
+ }
+ return;
+}
+
+int dummy_getinfo(int n)
+{
+ n-=4;
+ if ( fseek(in_file,n,SEEK_CUR) != 0)
+ {
+ if (feof(in_file))
+ return GETHDR_EOF;
+ else
+ return GETHDR_ERR;
+ }
+ return 0;
+}
+
+int rewind_stream(int nbytes)
+{
+ nbytes+=5;
+ if (fseek(in_file, -nbytes, SEEK_CUR) != 0) {
+ /* what if we need to be at the very beginning? */
+ nbytes--;
+ if (fseek(in_file, -nbytes, SEEK_CUR) != 0) return GETHDR_ERR;
+ }
+ return 0;
+}
+
+static inline int get_input(unsigned char* bp, unsigned int size)
+{
+#ifdef LINUX_REALTIME
+ return prefetch_get_input(bp,size);
+#else /* LINUX_REALTIME */
+ if ( fread( bp , 1, size, in_file) != size)
+ {
+ if (feof(in_file))
+ return GETHDR_EOF;
+ else
+ return GETHDR_ERR;
+ }
+ return 0;
+#endif /* LINUX_REALTIME */
+}
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