WinPrevious()

static void fl::third_party::WinPrevious ( int32_t * xPrev, int32_t * xPrevWin, int32_t btPrev )

static

Definition at line 141 of file imdct.hpp.

{
    int32_t i;
    int32_t x, *xp, *xpwLo, *xpwHi, wLo, wHi;
    const int32_t *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);
        }
    }
}

References FL_NOEXCEPT, imdctWin, MULSHIFT32(), and fl::x.

Referenced by HybridTransform(), IMDCT12x3(), and IMDCT36().

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