+#include <stdio.h>
+#include <string.h>
+
+#include "../../Pico/sound/mix.h"
+#include "code940/940shared.h"
+#include "helix/pub/mp3dec.h"
+
+static short mp3_out_buffer[2*1152];
+static HMP3Decoder mp3dec = 0;
+static int mp3_buffer_offs = 0;
+
+extern _940_ctl_t *shared_ctl;
+extern unsigned char *mp3_mem;
+extern int PsndRate;
+
+
+static int try_get_header(unsigned char *buff, MP3FrameInfo *fi)
+{
+ int ret, offs1, offs = 0;
+
+ while (1)
+ {
+ offs1 = MP3FindSyncWord(buff + offs, 2048 - offs);
+ if (offs1 < 0) return -2;
+ offs += offs1;
+ if (2048 - offs < 4) return -3;
+
+ // printf("trying header %08x\n", *(int *)(buff + offs));
+
+ ret = MP3GetNextFrameInfo(mp3dec, fi, buff + offs);
+ if (ret == 0 && fi->bitrate != 0) break;
+ offs++;
+ }
+
+ return ret;
+}
+
+int mp3_get_bitrate(FILE *f, int len)
+{
+ unsigned char buff[2048];
+ MP3FrameInfo fi;
+ int ret;
+
+ memset(buff, 0, 2048);
+
+ if (!mp3dec) mp3dec = MP3InitDecoder();
+
+ fseek(f, 0, SEEK_SET);
+ ret = fread(buff, 1, 2048, f);
+ fseek(f, 0, SEEK_SET);
+ if (ret <= 0) return -1;
+
+ ret = try_get_header(buff, &fi);
+ if (ret != 0 || fi.bitrate == 0) {
+ // try to read somewhere around the middle
+ fseek(f, len>>1, SEEK_SET);
+ fread(buff, 1, 2048, f);
+ fseek(f, 0, SEEK_SET);
+ ret = try_get_header(buff, &fi);
+ }
+ if (ret != 0) return ret;
+
+ // printf("bitrate: %i\n", fi.bitrate / 1000);
+
+ return fi.bitrate / 1000;
+}
+
+
+static void mp3_decode(void)
+{
+ // tried copying this to cached mem, no improvement noticed
+ int mp3_offs = shared_ctl->mp3_offs;
+ unsigned char *readPtr = mp3_mem + mp3_offs;
+ int bytesLeft = shared_ctl->mp3_len - mp3_offs;
+ int offset; // frame offset from readPtr
+ int err;
+
+ if (bytesLeft <= 0) return; // EOF, nothing to do
+
+ offset = MP3FindSyncWord(readPtr, bytesLeft);
+ if (offset < 0) {
+ shared_ctl->mp3_offs = shared_ctl->mp3_len;
+ return; // EOF
+ }
+ readPtr += offset;
+ bytesLeft -= offset;
+
+ err = MP3Decode(mp3dec, &readPtr, &bytesLeft, mp3_out_buffer, 0);
+ if (err) {
+ if (err == ERR_MP3_INDATA_UNDERFLOW) {
+ shared_ctl->mp3_offs = shared_ctl->mp3_len; // EOF
+ return;
+ } else if (err <= -6 && err >= -12) {
+ // ERR_MP3_INVALID_FRAMEHEADER, ERR_MP3_INVALID_*
+ // just try to skip the offending frame..
+ readPtr++;
+ }
+ shared_ctl->mp3_errors++;
+ shared_ctl->mp3_lasterr = err;
+ }
+ shared_ctl->mp3_offs = readPtr - mp3_mem;
+}
+
+
+void mp3_update_local(int *buffer, int length, int stereo)
+{
+ int length_mp3, shr = 0;
+ void (*mix_samples)(int *dest_buf, short *mp3_buf, int count) = mix_16h_to_32;
+
+ length_mp3 = length;
+ if (PsndRate == 22050) { mix_samples = mix_16h_to_32_s1; length_mp3 <<= 1; shr = 1; }
+ else if (PsndRate == 11025) { mix_samples = mix_16h_to_32_s2; length_mp3 <<= 2; shr = 2; }
+
+ if (1152 - mp3_buffer_offs >= length_mp3) {
+ mix_samples(buffer, mp3_out_buffer + mp3_buffer_offs*2, length<<1);
+
+ mp3_buffer_offs += length_mp3;
+ } else {
+ int left = 1152 - mp3_buffer_offs;
+
+ mix_samples(buffer, mp3_out_buffer + mp3_buffer_offs*2, (left>>shr)<<1);
+ mp3_decode();
+ mp3_buffer_offs = length_mp3 - left;
+ mix_samples(buffer + ((left>>shr)<<1), mp3_out_buffer, (mp3_buffer_offs>>shr)<<1);
+ }
+}
+
+
+void mp3_start_local(void)
+{
+ mp3_buffer_offs = 0;
+ mp3_decode();
+}
+