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| -rw-r--r-- | circuitpython/lib/mp3/src/imdct.c | 784 |
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diff --git a/circuitpython/lib/mp3/src/imdct.c b/circuitpython/lib/mp3/src/imdct.c new file mode 100644 index 0000000..53fda49 --- /dev/null +++ b/circuitpython/lib/mp3/src/imdct.c @@ -0,0 +1,784 @@ +/* ***** BEGIN LICENSE BLOCK ***** + * Version: RCSL 1.0/RPSL 1.0 + * + * Portions Copyright (c) 1995-2002 RealNetworks, Inc. All Rights Reserved. + * + * The contents of this file, and the files included with this file, are + * subject to the current version of the RealNetworks Public Source License + * Version 1.0 (the "RPSL") available at + * http://www.helixcommunity.org/content/rpsl unless you have licensed + * the file under the RealNetworks Community Source License Version 1.0 + * (the "RCSL") available at http://www.helixcommunity.org/content/rcsl, + * in which case the RCSL will apply. You may also obtain the license terms + * directly from RealNetworks. You may not use this file except in + * compliance with the RPSL or, if you have a valid RCSL with RealNetworks + * applicable to this file, the RCSL. Please see the applicable RPSL or + * RCSL for the rights, obligations and limitations governing use of the + * contents of the file. + * + * This file is part of the Helix DNA Technology. RealNetworks is the + * developer of the Original Code and owns the copyrights in the portions + * it created. + * + * This file, and the files included with this file, is distributed and made + * available on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER + * EXPRESS OR IMPLIED, AND REALNETWORKS HEREBY DISCLAIMS ALL SUCH WARRANTIES, + * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY, FITNESS + * FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT. + * + * Technology Compatibility Kit Test Suite(s) Location: + * http://www.helixcommunity.org/content/tck + * + * Contributor(s): + * + * ***** END LICENSE BLOCK ***** */ + +/************************************************************************************** + * Fixed-point MP3 decoder + * Jon Recker (jrecker@real.com), Ken Cooke (kenc@real.com) + * June 2003 + * + * imdct.c - antialias, inverse transform (short/long/mixed), windowing, + * overlap-add, frequency inversion + **************************************************************************************/ + +#include "coder.h" +#include "assembly.h" +#include <stdint.h> + +/************************************************************************************** + * Function: AntiAlias + * + * Description: smooth transition across DCT block boundaries (every 18 coefficients) + * + * Inputs: vector of dequantized coefficients, length = (nBfly+1) * 18 + * number of "butterflies" to perform (one butterfly means one + * inter-block smoothing operation) + * + * Outputs: updated coefficient vector x + * + * Return: none + * + * Notes: weighted average of opposite bands (pairwise) from the 8 samples + * before and after each block boundary + * nBlocks = (nonZeroBound + 7) / 18, since nZB is the first ZERO sample + * above which all other samples are also zero + * max gain per sample = 1.372 + * MAX(i) (abs(csa[i][0]) + abs(csa[i][1])) + * bits gained = 0 + * assume at least 1 guard bit in x[] to avoid overflow + * (should be guaranteed from dequant, and max gain from stproc * max + * gain from AntiAlias < 2.0) + **************************************************************************************/ +// a little bit faster in RAM (< 1 ms per block) +/* __attribute__ ((section (".data"))) */ static void AntiAlias(int *x, int nBfly) +{ + int k, a0, b0, c0, c1; + const int *c; + + /* csa = Q31 */ + for (k = nBfly; k > 0; k--) { + c = csa[0]; + x += 18; + + a0 = x[-1]; c0 = *c; c++; b0 = x[0]; c1 = *c; c++; + x[-1] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[0] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + + a0 = x[-2]; c0 = *c; c++; b0 = x[1]; c1 = *c; c++; + x[-2] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[1] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + + a0 = x[-3]; c0 = *c; c++; b0 = x[2]; c1 = *c; c++; + x[-3] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[2] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + + a0 = x[-4]; c0 = *c; c++; b0 = x[3]; c1 = *c; c++; + x[-4] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[3] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + + a0 = x[-5]; c0 = *c; c++; b0 = x[4]; c1 = *c; c++; + x[-5] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[4] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + + a0 = x[-6]; c0 = *c; c++; b0 = x[5]; c1 = *c; c++; + x[-6] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[5] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + + a0 = x[-7]; c0 = *c; c++; b0 = x[6]; c1 = *c; c++; + x[-7] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[6] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + + a0 = x[-8]; c0 = *c; c++; b0 = x[7]; c1 = *c; c++; + x[-8] = (MULSHIFT32(c0, a0) - MULSHIFT32(c1, b0)) << 1; + x[7] = (MULSHIFT32(c0, b0) + MULSHIFT32(c1, a0)) << 1; + } +} + +/************************************************************************************** + * Function: WinPrevious + * + * Description: apply specified window to second half of previous IMDCT (overlap part) + * + * Inputs: vector of 9 coefficients (xPrev) + * + * Outputs: 18 windowed output coefficients (gain 1 integer bit) + * window type (0, 1, 2, 3) + * + * Return: none + * + * Notes: produces 9 output samples from 18 input samples via symmetry + * all blocks gain at least 1 guard bit via window (long blocks get extra + * sign bit, short blocks can have one addition but max gain < 1.0) + **************************************************************************************/ +static void WinPrevious(int *xPrev, int *xPrevWin, int btPrev) +{ + int i, x, *xp, *xpwLo, *xpwHi, wLo, wHi; + const int *wpLo, *wpHi; + + xp = xPrev; + /* mapping (see IMDCT12x3): xPrev[0-2] = sum[6-8], xPrev[3-8] = sum[12-17] */ + if (btPrev == 2) { + /* this could be reordered for minimum loads/stores */ + wpLo = imdctWin[btPrev]; + xPrevWin[ 0] = MULSHIFT32(wpLo[ 6], xPrev[2]) + MULSHIFT32(wpLo[0], xPrev[6]); + xPrevWin[ 1] = MULSHIFT32(wpLo[ 7], xPrev[1]) + MULSHIFT32(wpLo[1], xPrev[7]); + xPrevWin[ 2] = MULSHIFT32(wpLo[ 8], xPrev[0]) + MULSHIFT32(wpLo[2], xPrev[8]); + xPrevWin[ 3] = MULSHIFT32(wpLo[ 9], xPrev[0]) + MULSHIFT32(wpLo[3], xPrev[8]); + xPrevWin[ 4] = MULSHIFT32(wpLo[10], xPrev[1]) + MULSHIFT32(wpLo[4], xPrev[7]); + xPrevWin[ 5] = MULSHIFT32(wpLo[11], xPrev[2]) + MULSHIFT32(wpLo[5], xPrev[6]); + xPrevWin[ 6] = MULSHIFT32(wpLo[ 6], xPrev[5]); + xPrevWin[ 7] = MULSHIFT32(wpLo[ 7], xPrev[4]); + xPrevWin[ 8] = MULSHIFT32(wpLo[ 8], xPrev[3]); + xPrevWin[ 9] = MULSHIFT32(wpLo[ 9], xPrev[3]); + xPrevWin[10] = MULSHIFT32(wpLo[10], xPrev[4]); + xPrevWin[11] = MULSHIFT32(wpLo[11], xPrev[5]); + xPrevWin[12] = xPrevWin[13] = xPrevWin[14] = xPrevWin[15] = xPrevWin[16] = xPrevWin[17] = 0; + } else { + /* use ARM-style pointers (*ptr++) so that ADS compiles well */ + wpLo = imdctWin[btPrev] + 18; + wpHi = wpLo + 17; + xpwLo = xPrevWin; + xpwHi = xPrevWin + 17; + for (i = 9; i > 0; i--) { + x = *xp++; wLo = *wpLo++; wHi = *wpHi--; + *xpwLo++ = MULSHIFT32(wLo, x); + *xpwHi-- = MULSHIFT32(wHi, x); + } + } +} + +/************************************************************************************** + * Function: FreqInvertRescale + * + * Description: do frequency inversion (odd samples of odd blocks) and rescale + * if necessary (extra guard bits added before IMDCT) + * + * Inputs: output vector y (18 new samples, spaced NBANDS apart) + * previous sample vector xPrev (9 samples) + * index of current block + * number of extra shifts added before IMDCT (usually 0) + * + * Outputs: inverted and rescaled (as necessary) outputs + * rescaled (as necessary) previous samples + * + * Return: updated mOut (from new outputs y) + **************************************************************************************/ +static int FreqInvertRescale(int *y, int *xPrev, int blockIdx, int es) +{ + int i, d, mOut; + int y0, y1, y2, y3, y4, y5, y6, y7, y8; + + if (es == 0) { + /* fast case - frequency invert only (no rescaling) - can fuse into overlap-add for speed, if desired */ + if (blockIdx & 0x01) { + y += NBANDS; + y0 = *y; y += 2*NBANDS; + y1 = *y; y += 2*NBANDS; + y2 = *y; y += 2*NBANDS; + y3 = *y; y += 2*NBANDS; + y4 = *y; y += 2*NBANDS; + y5 = *y; y += 2*NBANDS; + y6 = *y; y += 2*NBANDS; + y7 = *y; y += 2*NBANDS; + y8 = *y; y += 2*NBANDS; + + y -= 18*NBANDS; + *y = -y0; y += 2*NBANDS; + *y = -y1; y += 2*NBANDS; + *y = -y2; y += 2*NBANDS; + *y = -y3; y += 2*NBANDS; + *y = -y4; y += 2*NBANDS; + *y = -y5; y += 2*NBANDS; + *y = -y6; y += 2*NBANDS; + *y = -y7; y += 2*NBANDS; + *y = -y8; y += 2*NBANDS; + } + return 0; + } else { + /* undo pre-IMDCT scaling, clipping if necessary */ + mOut = 0; + if (blockIdx & 0x01) { + /* frequency invert */ + for (i = 0; i < 18; i+=2) { + d = *y; CLIP_2N(d, 31 - es); *y = d << es; mOut |= FASTABS(*y); y += NBANDS; + d = -*y; CLIP_2N(d, 31 - es); *y = d << es; mOut |= FASTABS(*y); y += NBANDS; + d = *xPrev; CLIP_2N(d, 31 - es); *xPrev++ = d << es; + } + } else { + for (i = 0; i < 18; i+=2) { + d = *y; CLIP_2N(d, 31 - es); *y = d << es; mOut |= FASTABS(*y); y += NBANDS; + d = *y; CLIP_2N(d, 31 - es); *y = d << es; mOut |= FASTABS(*y); y += NBANDS; + d = *xPrev; CLIP_2N(d, 31 - es); *xPrev++ = d << es; + } + } + return mOut; + } +} + +/* format = Q31 + * #define M_PI 3.14159265358979323846 + * double u = 2.0 * M_PI / 9.0; + * float c0 = sqrt(3.0) / 2.0; + * float c1 = cos(u); + * float c2 = cos(2*u); + * float c3 = sin(u); + * float c4 = sin(2*u); + */ +static const int c9_0 = 0x6ed9eba1; +static const int c9_1 = 0x620dbe8b; +static const int c9_2 = 0x163a1a7e; +static const int c9_3 = 0x5246dd49; +static const int c9_4 = 0x7e0e2e32; + +/* format = Q31 + * cos(((0:8) + 0.5) * (pi/18)) + */ +static const int c18[9] = { + 0x7f834ed0, 0x7ba3751d, 0x7401e4c1, 0x68d9f964, 0x5a82799a, 0x496af3e2, 0x36185aee, 0x2120fb83, 0x0b27eb5c, +}; + +/* require at least 3 guard bits in x[] to ensure no overflow */ +static __inline void idct9(int *x) +{ + int a1, a2, a3, a4, a5, a6, a7, a8, a9; + int a10, a11, a12, a13, a14, a15, a16, a17, a18; + int a19, a20, a21, a22, a23, a24, a25, a26, a27; + int m1, m3, m5, m6, m7, m8, m9, m10, m11, m12; + int x0, x1, x2, x3, x4, x5, x6, x7, x8; + + x0 = x[0]; x1 = x[1]; x2 = x[2]; x3 = x[3]; x4 = x[4]; + x5 = x[5]; x6 = x[6]; x7 = x[7]; x8 = x[8]; + + a1 = x0 - x6; + a2 = x1 - x5; + a3 = x1 + x5; + a4 = x2 - x4; + a5 = x2 + x4; + a6 = x2 + x8; + a7 = x1 + x7; + + a8 = a6 - a5; /* ie x[8] - x[4] */ + a9 = a3 - a7; /* ie x[5] - x[7] */ + a10 = a2 - x7; /* ie x[1] - x[5] - x[7] */ + a11 = a4 - x8; /* ie x[2] - x[4] - x[8] */ + + /* do the << 1 as constant shifts where mX is actually used (free, no stall or extra inst.) */ + m1 = MULSHIFT32(c9_0, x3); + m3 = MULSHIFT32(c9_0, a10); + m5 = MULSHIFT32(c9_1, a5); + m6 = MULSHIFT32(c9_2, a6); + m7 = MULSHIFT32(c9_1, a8); + m8 = MULSHIFT32(c9_2, a5); + m9 = MULSHIFT32(c9_3, a9); + m10 = MULSHIFT32(c9_4, a7); + m11 = MULSHIFT32(c9_3, a3); + m12 = MULSHIFT32(c9_4, a9); + + a12 = x[0] + (x[6] >> 1); + a13 = a12 + ( m1 << 1); + a14 = a12 - ( m1 << 1); + a15 = a1 + ( a11 >> 1); + a16 = ( m5 << 1) + (m6 << 1); + a17 = ( m7 << 1) - (m8 << 1); + a18 = a16 + a17; + a19 = ( m9 << 1) + (m10 << 1); + a20 = (m11 << 1) - (m12 << 1); + + a21 = a20 - a19; + a22 = a13 + a16; + a23 = a14 + a16; + a24 = a14 + a17; + a25 = a13 + a17; + a26 = a14 - a18; + a27 = a13 - a18; + + x0 = a22 + a19; x[0] = x0; + x1 = a15 + (m3 << 1); x[1] = x1; + x2 = a24 + a20; x[2] = x2; + x3 = a26 - a21; x[3] = x3; + x4 = a1 - a11; x[4] = x4; + x5 = a27 + a21; x[5] = x5; + x6 = a25 - a20; x[6] = x6; + x7 = a15 - (m3 << 1); x[7] = x7; + x8 = a23 - a19; x[8] = x8; +} + +/* let c(j) = cos(M_PI/36 * ((j)+0.5)), s(j) = sin(M_PI/36 * ((j)+0.5)) + * then fastWin[2*j+0] = c(j)*(s(j) + c(j)), j = [0, 8] + * fastWin[2*j+1] = c(j)*(s(j) - c(j)) + * format = Q30 + */ +static const int fastWin36[18] = { + (int32_t)0x42aace8b, (int32_t)0xc2e92724, (int32_t)0x47311c28, (int32_t)0xc95f619a, (int32_t)0x4a868feb, (int32_t)0xd0859d8c, + (int32_t)0x4c913b51, (int32_t)0xd8243ea0, (int32_t)0x4d413ccc, (int32_t)0xe0000000, (int32_t)0x4c913b51, (int32_t)0xe7dbc161, + (int32_t)0x4a868feb, (int32_t)0xef7a6275, (int32_t)0x47311c28, (int32_t)0xf6a09e67, (int32_t)0x42aace8b, (int32_t)0xfd16d8dd, +}; + +/************************************************************************************** + * Function: IMDCT36 + * + * Description: 36-point modified DCT, with windowing and overlap-add (50% overlap) + * + * Inputs: vector of 18 coefficients (N/2 inputs produces N outputs, by symmetry) + * overlap part of last IMDCT (9 samples - see output comments) + * window type (0,1,2,3) of current and previous block + * current block index (for deciding whether to do frequency inversion) + * number of guard bits in input vector + * + * Outputs: 18 output samples, after windowing and overlap-add with last frame + * second half of (unwindowed) 36-point IMDCT - save for next time + * only save 9 xPrev samples, using symmetry (see WinPrevious()) + * + * Notes: this is Ken's hyper-fast algorithm, including symmetric sin window + * optimization, if applicable + * total number of multiplies, general case: + * 2*10 (idct9) + 9 (last stage imdct) + 36 (for windowing) = 65 + * total number of multiplies, btCurr == 0 && btPrev == 0: + * 2*10 (idct9) + 9 (last stage imdct) + 18 (for windowing) = 47 + * + * blockType == 0 is by far the most common case, so it should be + * possible to use the fast path most of the time + * this is the fastest known algorithm for performing + * long IMDCT + windowing + overlap-add in MP3 + * + * Return: mOut (OR of abs(y) for all y calculated here) + * + * TODO: optimize for ARM (reorder window coefs, ARM-style pointers in C, + * inline asm may or may not be helpful) + **************************************************************************************/ +// barely faster in RAM +/*__attribute__ ((section (".data")))*/ static int IMDCT36(int *xCurr, int *xPrev, int *y, int btCurr, int btPrev, int blockIdx, int gb) +{ + int i, es, xBuf[18], xPrevWin[18]; + int acc1, acc2, s, d, t, mOut; + int xo, xe, c, *xp, yLo, yHi; + const int *cp, *wp; + + acc1 = acc2 = 0; + xCurr += 17; + + /* 7 gb is always adequate for antialias + accumulator loop + idct9 */ + if (gb < 7) { + /* rarely triggered - 5% to 10% of the time on normal clips (with Q25 input) */ + es = 7 - gb; + for (i = 8; i >= 0; i--) { + acc1 = ((*xCurr--) >> es) - acc1; + acc2 = acc1 - acc2; + acc1 = ((*xCurr--) >> es) - acc1; + xBuf[i+9] = acc2; /* odd */ + xBuf[i+0] = acc1; /* even */ + xPrev[i] >>= es; + } + } else { + es = 0; + /* max gain = 18, assume adequate guard bits */ + for (i = 8; i >= 0; i--) { + acc1 = (*xCurr--) - acc1; + acc2 = acc1 - acc2; + acc1 = (*xCurr--) - acc1; + xBuf[i+9] = acc2; /* odd */ + xBuf[i+0] = acc1; /* even */ + } + } + /* xEven[0] and xOdd[0] scaled by 0.5 */ + xBuf[9] >>= 1; + xBuf[0] >>= 1; + + /* do 9-point IDCT on even and odd */ + idct9(xBuf+0); /* even */ + idct9(xBuf+9); /* odd */ + + xp = xBuf + 8; + cp = c18 + 8; + mOut = 0; + if (btPrev == 0 && btCurr == 0) { + /* fast path - use symmetry of sin window to reduce windowing multiplies to 18 (N/2) */ + wp = fastWin36; + for (i = 0; i < 9; i++) { + /* do ARM-style pointer arithmetic (i still needed for y[] indexing - compiler spills if 2 y pointers) */ + c = *cp--; xo = *(xp + 9); xe = *xp--; + /* gain 2 int bits here */ + xo = MULSHIFT32(c, xo); /* 2*c18*xOdd (mul by 2 implicit in scaling) */ + xe >>= 2; + + s = -(*xPrev); /* sum from last block (always at least 2 guard bits) */ + d = -(xe - xo); /* gain 2 int bits, don't shift xo (effective << 1 to eat sign bit, << 1 for mul by 2) */ + (*xPrev++) = xe + xo; /* symmetry - xPrev[i] = xPrev[17-i] for long blocks */ + t = s - d; + + yLo = (d + (MULSHIFT32(t, *wp++) << 2)); + yHi = (s + (MULSHIFT32(t, *wp++) << 2)); + y[(i)*NBANDS] = yLo; + y[(17-i)*NBANDS] = yHi; + mOut |= FASTABS(yLo); + mOut |= FASTABS(yHi); + } + } else { + /* slower method - either prev or curr is using window type != 0 so do full 36-point window + * output xPrevWin has at least 3 guard bits (xPrev has 2, gain 1 in WinPrevious) + */ + WinPrevious(xPrev, xPrevWin, btPrev); + + wp = imdctWin[btCurr]; + for (i = 0; i < 9; i++) { + c = *cp--; xo = *(xp + 9); xe = *xp--; + /* gain 2 int bits here */ + xo = MULSHIFT32(c, xo); /* 2*c18*xOdd (mul by 2 implicit in scaling) */ + xe >>= 2; + + d = xe - xo; + (*xPrev++) = xe + xo; /* symmetry - xPrev[i] = xPrev[17-i] for long blocks */ + + yLo = (xPrevWin[i] + MULSHIFT32(d, wp[i])) << 2; + yHi = (xPrevWin[17-i] + MULSHIFT32(d, wp[17-i])) << 2; + y[(i)*NBANDS] = yLo; + y[(17-i)*NBANDS] = yHi; + mOut |= FASTABS(yLo); + mOut |= FASTABS(yHi); + } + } + + xPrev -= 9; + mOut |= FreqInvertRescale(y, xPrev, blockIdx, es); + + return mOut; +} + +static const int c3_0 = (int32_t)0x6ed9eba1; /* format = Q31, cos(pi/6) */ +static const int c6[3] = { (int32_t)0x7ba3751d, (int32_t)0x5a82799a, (int32_t)0x2120fb83 }; /* format = Q31, cos(((0:2) + 0.5) * (pi/6)) */ + +/* 12-point inverse DCT, used in IMDCT12x3() + * 4 input guard bits will ensure no overflow + */ +static __inline void imdct12 (int *x, int *out) +{ + int a0, a1, a2; + int x0, x1, x2, x3, x4, x5; + + x0 = *x; x+=3; x1 = *x; x+=3; + x2 = *x; x+=3; x3 = *x; x+=3; + x4 = *x; x+=3; x5 = *x; x+=3; + + x4 -= x5; + x3 -= x4; + x2 -= x3; + x3 -= x5; + x1 -= x2; + x0 -= x1; + x1 -= x3; + + x0 >>= 1; + x1 >>= 1; + + a0 = MULSHIFT32(c3_0, x2) << 1; + a1 = x0 + (x4 >> 1); + a2 = x0 - x4; + x0 = a1 + a0; + x2 = a2; + x4 = a1 - a0; + + a0 = MULSHIFT32(c3_0, x3) << 1; + a1 = x1 + (x5 >> 1); + a2 = x1 - x5; + + /* cos window odd samples, mul by 2, eat sign bit */ + x1 = MULSHIFT32(c6[0], a1 + a0) << 2; + x3 = MULSHIFT32(c6[1], a2) << 2; + x5 = MULSHIFT32(c6[2], a1 - a0) << 2; + + *out = x0 + x1; out++; + *out = x2 + x3; out++; + *out = x4 + x5; out++; + *out = x4 - x5; out++; + *out = x2 - x3; out++; + *out = x0 - x1; +} + +/************************************************************************************** + * Function: IMDCT12x3 + * + * Description: three 12-point modified DCT's for short blocks, with windowing, + * short block concatenation, and overlap-add + * + * Inputs: 3 interleaved vectors of 6 samples each + * (block0[0], block1[0], block2[0], block0[1], block1[1]....) + * overlap part of last IMDCT (9 samples - see output comments) + * window type (0,1,2,3) of previous block + * current block index (for deciding whether to do frequency inversion) + * number of guard bits in input vector + * + * Outputs: updated sample vector x, net gain of 1 integer bit + * second half of (unwindowed) IMDCT's - save for next time + * only save 9 xPrev samples, using symmetry (see WinPrevious()) + * + * Return: mOut (OR of abs(y) for all y calculated here) + * + * TODO: optimize for ARM + **************************************************************************************/ + // barely faster in RAM +/*__attribute__ ((section (".data")))*/ static int IMDCT12x3(int *xCurr, int *xPrev, int *y, int btPrev, int blockIdx, int gb) +{ + int i, es, mOut, yLo, xBuf[18], xPrevWin[18]; /* need temp buffer for reordering short blocks */ + const int *wp; + + es = 0; + /* 7 gb is always adequate for accumulator loop + idct12 + window + overlap */ + if (gb < 7) { + es = 7 - gb; + for (i = 0; i < 18; i+=2) { + xCurr[i+0] >>= es; + xCurr[i+1] >>= es; + *xPrev++ >>= es; + } + xPrev -= 9; + } + + /* requires 4 input guard bits for each imdct12 */ + imdct12(xCurr + 0, xBuf + 0); + imdct12(xCurr + 1, xBuf + 6); + imdct12(xCurr + 2, xBuf + 12); + + /* window previous from last time */ + WinPrevious(xPrev, xPrevWin, btPrev); + + /* could unroll this for speed, minimum loads (short blocks usually rare, so doesn't make much overall difference) + * xPrevWin[i] << 2 still has 1 gb always, max gain of windowed xBuf stuff also < 1.0 and gain the sign bit + * so y calculations won't overflow + */ + wp = imdctWin[2]; + mOut = 0; + for (i = 0; i < 3; i++) { + yLo = (xPrevWin[ 0+i] << 2); + mOut |= FASTABS(yLo); y[( 0+i)*NBANDS] = yLo; + yLo = (xPrevWin[ 3+i] << 2); + mOut |= FASTABS(yLo); y[( 3+i)*NBANDS] = yLo; + yLo = (xPrevWin[ 6+i] << 2) + (MULSHIFT32(wp[0+i], xBuf[3+i])); + mOut |= FASTABS(yLo); y[( 6+i)*NBANDS] = yLo; + yLo = (xPrevWin[ 9+i] << 2) + (MULSHIFT32(wp[3+i], xBuf[5-i])); + mOut |= FASTABS(yLo); y[( 9+i)*NBANDS] = yLo; + yLo = (xPrevWin[12+i] << 2) + (MULSHIFT32(wp[6+i], xBuf[2-i]) + MULSHIFT32(wp[0+i], xBuf[(6+3)+i])); + mOut |= FASTABS(yLo); y[(12+i)*NBANDS] = yLo; + yLo = (xPrevWin[15+i] << 2) + (MULSHIFT32(wp[9+i], xBuf[0+i]) + MULSHIFT32(wp[3+i], xBuf[(6+5)-i])); + mOut |= FASTABS(yLo); y[(15+i)*NBANDS] = yLo; + } + + /* save previous (unwindowed) for overlap - only need samples 6-8, 12-17 */ + for (i = 6; i < 9; i++) + *xPrev++ = xBuf[i] >> 2; + for (i = 12; i < 18; i++) + *xPrev++ = xBuf[i] >> 2; + + xPrev -= 9; + mOut |= FreqInvertRescale(y, xPrev, blockIdx, es); + + return mOut; +} + +/************************************************************************************** + * Function: HybridTransform + * + * Description: IMDCT's, windowing, and overlap-add on long/short/mixed blocks + * + * Inputs: vector of input coefficients, length = nBlocksTotal * 18) + * vector of overlap samples from last time, length = nBlocksPrev * 9) + * buffer for output samples, length = MAXNSAMP + * SideInfoSub struct for this granule/channel + * BlockCount struct with necessary info + * number of non-zero input and overlap blocks + * number of long blocks in input vector (rest assumed to be short blocks) + * number of blocks which use long window (type) 0 in case of mixed block + * (bc->currWinSwitch, 0 for non-mixed blocks) + * + * Outputs: transformed, windowed, and overlapped sample buffer + * does frequency inversion on odd blocks + * updated buffer of samples for overlap + * + * Return: number of non-zero IMDCT blocks calculated in this call + * (including overlap-add) + * + * TODO: examine mixedBlock/winSwitch logic carefully (test he_mode.bit) + **************************************************************************************/ +static int HybridTransform(int *xCurr, int *xPrev, int y[BLOCK_SIZE][NBANDS], SideInfoSub *sis, BlockCount *bc) +{ + int xPrevWin[18], currWinIdx, prevWinIdx; + int i, j, nBlocksOut, nonZero, mOut; + int fiBit, xp; + + ASSERT(bc->nBlocksLong <= NBANDS); + ASSERT(bc->nBlocksTotal <= NBANDS); + ASSERT(bc->nBlocksPrev <= NBANDS); + + mOut = 0; + + /* do long blocks, if any */ + for(i = 0; i < bc->nBlocksLong; i++) { + /* currWinIdx picks the right window for long blocks (if mixed, long blocks use window type 0) */ + currWinIdx = sis->blockType; + if (sis->mixedBlock && i < bc->currWinSwitch) + currWinIdx = 0; + + prevWinIdx = bc->prevType; + if (i < bc->prevWinSwitch) + prevWinIdx = 0; + + /* do 36-point IMDCT, including windowing and overlap-add */ + mOut |= IMDCT36(xCurr, xPrev, &(y[0][i]), currWinIdx, prevWinIdx, i, bc->gbIn); + xCurr += 18; + xPrev += 9; + } + + /* do short blocks (if any) */ + for ( ; i < bc->nBlocksTotal; i++) { + ASSERT(sis->blockType == 2); + + prevWinIdx = bc->prevType; + if (i < bc->prevWinSwitch) + prevWinIdx = 0; + + mOut |= IMDCT12x3(xCurr, xPrev, &(y[0][i]), prevWinIdx, i, bc->gbIn); + xCurr += 18; + xPrev += 9; + } + nBlocksOut = i; + + /* window and overlap prev if prev longer that current */ + for ( ; i < bc->nBlocksPrev; i++) { + prevWinIdx = bc->prevType; + if (i < bc->prevWinSwitch) + prevWinIdx = 0; + WinPrevious(xPrev, xPrevWin, prevWinIdx); + + nonZero = 0; + fiBit = i << 31; + for (j = 0; j < 9; j++) { + xp = xPrevWin[2*j+0] << 2; /* << 2 temp for scaling */ + nonZero |= xp; + y[2*j+0][i] = xp; + mOut |= FASTABS(xp); + + /* frequency inversion on odd blocks/odd samples (flip sign if i odd, j odd) */ + xp = xPrevWin[2*j+1] << 2; + xp = (xp ^ (fiBit >> 31)) + (i & 0x01); + nonZero |= xp; + y[2*j+1][i] = xp; + mOut |= FASTABS(xp); + + xPrev[j] = 0; + } + xPrev += 9; + if (nonZero) + nBlocksOut = i; + } + + /* clear rest of blocks */ + for ( ; i < 32; i++) { + for (j = 0; j < 18; j++) + y[j][i] = 0; + } + + bc->gbOut = CLZ(mOut) - 1; + + return nBlocksOut; +} + +/************************************************************************************** + * Function: IMDCT + * + * Description: do alias reduction, inverse MDCT, overlap-add, and frequency inversion + * + * Inputs: MP3DecInfo structure filled by UnpackFrameHeader(), UnpackSideInfo(), + * UnpackScaleFactors(), and DecodeHuffman() (for this granule, channel) + * includes PCM samples in overBuf (from last call to IMDCT) for OLA + * index of current granule and channel + * + * Outputs: PCM samples in outBuf, for input to subband transform + * PCM samples in overBuf, for OLA next time + * updated hi->nonZeroBound index for this channel + * + * Return: 0 on success, -1 if null input pointers + **************************************************************************************/ + // a bit faster in RAM +/*__attribute__ ((section (".data")))*/ int IMDCT(MP3DecInfo *mp3DecInfo, int gr, int ch) +{ + int nBfly, blockCutoff; + FrameHeader *fh; + SideInfo *si; + HuffmanInfo *hi; + IMDCTInfo *mi; + BlockCount bc; + + /* validate pointers */ + if (!mp3DecInfo || !mp3DecInfo->FrameHeaderPS || !mp3DecInfo->SideInfoPS || + !mp3DecInfo->HuffmanInfoPS || !mp3DecInfo->IMDCTInfoPS) + return -1; + + /* si is an array of up to 4 structs, stored as gr0ch0, gr0ch1, gr1ch0, gr1ch1 */ + fh = (FrameHeader *)(mp3DecInfo->FrameHeaderPS); + si = (SideInfo *)(mp3DecInfo->SideInfoPS); + hi = (HuffmanInfo*)(mp3DecInfo->HuffmanInfoPS); + mi = (IMDCTInfo *)(mp3DecInfo->IMDCTInfoPS); + + /* anti-aliasing done on whole long blocks only + * for mixed blocks, nBfly always 1, except 3 for 8 kHz MPEG 2.5 (see sfBandTab) + * nLongBlocks = number of blocks with (possibly) non-zero power + * nBfly = number of butterflies to do (nLongBlocks - 1, unless no long blocks) + */ + blockCutoff = fh->sfBand->l[(fh->ver == MPEG1 ? 8 : 6)] / 18; /* same as 3* num short sfb's in spec */ + if (si->sis[gr][ch].blockType != 2) { + /* all long transforms */ + bc.nBlocksLong = MIN((hi->nonZeroBound[ch] + 7) / 18 + 1, 32); + nBfly = bc.nBlocksLong - 1; + } else if (si->sis[gr][ch].blockType == 2 && si->sis[gr][ch].mixedBlock) { + /* mixed block - long transforms until cutoff, then short transforms */ + bc.nBlocksLong = blockCutoff; + nBfly = bc.nBlocksLong - 1; + } else { + /* all short transforms */ + bc.nBlocksLong = 0; + nBfly = 0; + } + + AntiAlias(hi->huffDecBuf[ch], nBfly); + hi->nonZeroBound[ch] = MAX(hi->nonZeroBound[ch], (nBfly * 18) + 8); + + ASSERT(hi->nonZeroBound[ch] <= MAX_NSAMP); + + /* for readability, use a struct instead of passing a million parameters to HybridTransform() */ + bc.nBlocksTotal = (hi->nonZeroBound[ch] + 17) / 18; + bc.nBlocksPrev = mi->numPrevIMDCT[ch]; + bc.prevType = mi->prevType[ch]; + bc.prevWinSwitch = mi->prevWinSwitch[ch]; + bc.currWinSwitch = (si->sis[gr][ch].mixedBlock ? blockCutoff : 0); /* where WINDOW switches (not nec. transform) */ + bc.gbIn = hi->gb[ch]; + + mi->numPrevIMDCT[ch] = HybridTransform(hi->huffDecBuf[ch], mi->overBuf[ch], mi->outBuf[ch], &si->sis[gr][ch], &bc); + mi->prevType[ch] = si->sis[gr][ch].blockType; + mi->prevWinSwitch[ch] = bc.currWinSwitch; /* 0 means not a mixed block (either all short or all long) */ + mi->gb[ch] = bc.gbOut; + + ASSERT(mi->numPrevIMDCT[ch] <= NBANDS); + + /* output has gained 2 int bits */ + return 0; +} |