Mp3算法在cortex上的移植

Mp3算法在 cortex上的移植 前些日子搞了一个产品，使用的是 cortex-m3芯片，涉及到音频部分，由于在裸板上做，Libmad 需要资源较多，所以就 helix_mp3 移植 1. 下载 helix_mp3包 2. 编辑\helix_mp3\real\assembly.h #ifndef _ASSEMBLY_H #define _ASSEMBLY_H static __inline int MULSHIFT32(int x, int y) { int ret; long long temp=x; temp = temp*y; ret = (int)(temp>>32); return ret; /* __asm { mov eax, x imul y mov eax, edx } */ } static __inline int FASTABS(int x) { int sign; sign = x >> (sizeof(int) * 8 - 1); x ^= sign; x -= sign; return x; } static __inline int CLZ(int x) { int numZeros; if (!x) return (sizeof(int) * 8); numZeros = 0; while (!(x & 0x80000000)) { numZeros++; x <<= 1; } return numZeros; } /* MADD64, SHL64, SAR64: * write in assembly to avoid dependency on run-time lib for 64-bit shifts, muls * (sometimes compiler thunks to function calls instead of code generating) * required for Symbian emulator */ //typedef long long __int64; //typedef __int64 Word64; static __inline long long MADD64(long long sum, int x, int y) { /* unsigned int sumLo = ((unsigned int *)&sum)[0]; int sumHi = ((int *)&sum)[1]; __asm { mov eax, x imul y add eax, sumLo adc edx, sumHi } */ return (sum + ((long long)x * y)); } /* static __inline Word64 SHL64(Word64 x, int n) { unsigned int xLo = ((unsigned int *)&x)[0]; int xHi = ((int *)&x)[1]; unsigned char nb = (unsigned char)n; if (n < 32) { __asm { mov edx, xHi mov eax, xLo mov cl, nb shld edx, eax, cl shl eax, cl } } else if (n < 64) { // shl masks cl to 0x1f __asm { mov edx, xLo mov cl, nb xor eax, eax shl edx, cl } } else { __asm { xor edx, edx xor eax, eax } } } */ static __inline long long SAR64(long long x, int n) { long long ret = x; ret = ret>>n; return ret; /* unsigned int xLo = ((unsigned int *)&x)[0]; int xHi = ((int *)&x)[1]; unsigned char nb = (unsigned char)n; // if (n < 32) { __asm { mov edx, xHi mov eax, xLo mov cl, nb shrd eax, edx, cl sar edx, cl } } else if (n < 64) { // sar masks cl to 0x1f __asm { mov edx, xHi mov eax, xHi mov cl, nb sar edx, 31 sar eax, cl } } else { __asm { sar xHi, 31 mov eax, xHi mov edx, xHi } } */ } #endif /* _ASSEMBLY_H */ 这里只把汇编转化为 C代码 使用 1. 环境MDK3.40 2. 加入文件 3. 增加路径 4. 加入头文件 a) #include "third_party/helix_mp3/pub/mp3dec.h" 5. 播放代码 if((g_ulFlags & BUFFER_PLAYING) && (g_ulFlags & BUFFER_PAUSE)==0) { if(g_pcmSel>=ONE_SMPLE_SIZE) { //somewhat arbitrary trigger to refill buffer – //should always be enough for a full frame if (bytesLeft < 2*MAINBUF_SIZE && !eofReached) { nRead = FillReadBuffer(readBuf, readPtr, READBUF_SIZE, bytesLeft, &g_sFileObject); bytesLeft += nRead; readPtr = readBuf; if (nRead == 0) eofReached = 1; } //find start of next MP3 frame - assume EOF if no sync found offset = MP3FindSyncWord(readPtr, bytesLeft); if (offset < 0) { outOfData = 1; //break; } else { readPtr += offset; bytesLeft -= offset; // decode one MP3 frame - if offset < 0 then bytesLeft was less than a full frame err=MP3Decode(hMP3Decoder, &readPtr, &bytesLeft,g_pcmBuf+4608-g_pcmSel, 0); nFrames++; if (err) // error occurred { switch (err) { case ERR_MP3_INDATA_UNDERFLOW: outOfData = 1; break; :// do nothing - next call to decode will provide more mainData case ERR_MP3_MAINDATA_UNDERFLOW break; case ERR_MP3_FREE_BITRATE_SYNC: default: outOfData = 1; break; } } else // no error { MP3GetLastFrameInfo(hMP3Decoder, &mp3FrameInfo); if(nFrames == 1) { usprintf(g_pcFormat, "%d Hz %d bit ", mp3FrameInfo.samprate,mp3FrameInfo.bitrate); if(mp3FrameInfo.nChans == 1) strcat(g_pcFormat, "Mono"); else strcat(g_pcFormat, "Stereo"); SoundSetFormat(mp3FrameInfo.samprate, mp3FrameInfo.bitsPerSample,mp3FrameInfo.nChans); } // if(xx > mp3FrameInfo.outputSamps) xx = 10; g_pcmSel -= mp3FrameInfo.outputSamps; } // udp_sendx((u8_t *)g_pucBuffer,xx); //将解码数据发送给服务端 } } //这里使用两个缓存，边解码边播放 if(g_pcmSel <= (MP3_DECODE_BUF_SIZE - 1024)) { if(g_ulFlags & BUFFER_BOTTOM_EMPTY) { memmove(g_pucBuffer,g_pcmBuf,1024*sizeof(short)); memmove(g_pcmBuf,g_pcmBuf+1024, (MP3_DECODE_BUF_SIZE-1024)*sizeof(short)); SoundBufferPlay(g_pucBuffer,1024*sizeof(short), BufferCallback); g_pcmSel+=1024; g_ulFlags &= ~BUFFER_BOTTOM_EMPTY; } else if(g_ulFlags & BUFFER_TOP_EMPTY) { memmove(&g_pucBuffer[AUDIO_BUFFER_SIZE>>1], g_pcmBuf,1024*sizeof(short)); memmove(g_pcmBuf,g_pcmBuf+1024, (MP3_DECODE_BUF_SIZE-1024)*sizeof(short)); g_pcmSel+=1024; SoundBufferPlay(&g_pucBuffer[AUDIO_BUFFER_SIZE>>1], 1024*sizeof(short), BufferCallback); g_ulFlags &= ~BUFFER_TOP_EMPTY; DisplayTime(); } } } 测试板子