mdct15: add assembly optimizations for the 15-point FFT

c:    1802 decicycles in fft15,16774635 runs,   2581 skips
avx:   865 decicycles in fft15,16776378 runs,    838 skips

Signed-off-by: Rostislav Pehlivanov <atomnuker@gmail.com>

5 files changed, 337 insertions, 109 deletions

diff --git a/libavcodec/mdct15.c b/libavcodec/mdct15.c
index 8c42ece483..f93881fbed 100644
--- a/libavcodec/mdct15.c
+++ b/libavcodec/mdct15.c
@@ -57,11 +57,6 @@ av_cold void ff_mdct15_uninit(MDCT15Context **ps)
     av_freep(ps);
 }
 
-static void mdct15(MDCT15Context *s, float *dst, const float *src, ptrdiff_t stride);
-
-static void imdct15_half(MDCT15Context *s, float *dst, const float *src,
-                         ptrdiff_t stride, float scale);
-
 static inline int init_pfa_reindex_tabs(MDCT15Context *s)
 {
     int i, j;
@@ -93,88 +88,8 @@ static inline int init_pfa_reindex_tabs(MDCT15Context *s)
     return 0;
 }
 
-av_cold int ff_mdct15_init(MDCT15Context **ps, int inverse, int N, double scale)
-{
-    MDCT15Context *s;
-    double alpha, theta;
-    int len2 = 15 * (1 << N);
-    int len  = 2 * len2;
-    int i;
-
-    /* Tested and verified to work on everything in between */
-    if ((N < 2) || (N > 13))
-        return AVERROR(EINVAL);
-
-    s = av_mallocz(sizeof(*s));
-    if (!s)
-        return AVERROR(ENOMEM);
-
-    s->fft_n = N - 1;
-    s->len4 = len2 / 2;
-    s->len2 = len2;
-    s->inverse = inverse;
-    s->mdct = mdct15;
-    s->imdct_half = imdct15_half;
-
-    if (ff_fft_init(&s->ptwo_fft, N - 1, s->inverse) < 0)
-        goto fail;
-
-    if (init_pfa_reindex_tabs(s))
-        goto fail;
-
-    s->tmp  = av_malloc_array(len, 2 * sizeof(*s->tmp));
-    if (!s->tmp)
-        goto fail;
-
-    s->twiddle_exptab  = av_malloc_array(s->len4, sizeof(*s->twiddle_exptab));
-    if (!s->twiddle_exptab)
-        goto fail;
-
-    theta = 0.125f + (scale < 0 ? s->len4 : 0);
-    scale = sqrt(fabs(scale));
-    for (i = 0; i < s->len4; i++) {
-        alpha = 2 * M_PI * (i + theta) / len;
-        s->twiddle_exptab[i].re = cos(alpha) * scale;
-        s->twiddle_exptab[i].im = sin(alpha) * scale;
-    }
-
-    /* 15-point FFT exptab */
-    for (i = 0; i < 19; i++) {
-        if (i < 15) {
-            double theta = (2.0f * M_PI * i) / 15.0f;
-            if (!s->inverse)
-                theta *= -1;
-            s->exptab[i].re = cos(theta);
-            s->exptab[i].im = sin(theta);
-        } else { /* Wrap around to simplify fft15 */
-            s->exptab[i] = s->exptab[i - 15];
-        }
-    }
-
-    /* 5-point FFT exptab */
-    s->exptab[19].re = cos(2.0f * M_PI / 5.0f);
-    s->exptab[19].im = sin(2.0f * M_PI / 5.0f);
-    s->exptab[20].re = cos(1.0f * M_PI / 5.0f);
-    s->exptab[20].im = sin(1.0f * M_PI / 5.0f);
-
-    /* Invert the phase for an inverse transform, do nothing for a forward transform */
-    if (s->inverse) {
-        s->exptab[19].im *= -1;
-        s->exptab[20].im *= -1;
-    }
-
-    *ps = s;
-
-    return 0;
-
-fail:
-    ff_mdct15_uninit(&s);
-    return AVERROR(ENOMEM);
-}
-
 /* Stride is hardcoded to 3 */
-static inline void fft5(const FFTComplex exptab[2], FFTComplex *out,
-                        const FFTComplex *in)
+static inline void fft5(FFTComplex *out, FFTComplex *in, FFTComplex exptab[2])
 {
     FFTComplex z0[4], t[6];
 
@@ -219,14 +134,14 @@ static inline void fft5(const FFTComplex exptab[2], FFTComplex *out,
     out[4].im = in[0].im + z0[3].im;
 }
 
-static void fft15(const FFTComplex exptab[22], FFTComplex *out, const FFTComplex *in, size_t stride)
+static void fft15_c(FFTComplex *out, FFTComplex *in, FFTComplex *exptab, ptrdiff_t stride)
 {
     int k;
     FFTComplex tmp1[5], tmp2[5], tmp3[5];
 
-    fft5(exptab + 19, tmp1, in + 0);
-    fft5(exptab + 19, tmp2, in + 1);
-    fft5(exptab + 19, tmp3, in + 2);
+    fft5(tmp1, in + 0, exptab + 19);
+    fft5(tmp2, in + 1, exptab + 19);
+    fft5(tmp3, in + 2, exptab + 19);
 
     for (k = 0; k < 5; k++) {
         FFTComplex t[2];
@@ -269,7 +184,7 @@ static void mdct15(MDCT15Context *s, float *dst, const float *src, ptrdiff_t str
             }
             CMUL(fft15in[j].re, fft15in[j].im, re, im, s->twiddle_exptab[k].re, -s->twiddle_exptab[k].im);
         }
-        fft15(s->exptab, s->tmp + s->ptwo_fft.revtab[i], fft15in, l_ptwo);
+        s->fft15(s->tmp + s->ptwo_fft.revtab[i], fft15in, s->exptab, l_ptwo);
     }
 
     /* Then a 15xN FFT (where N is a power of two) */
@@ -306,7 +221,7 @@ static void imdct15_half(MDCT15Context *s, float *dst, const float *src,
             FFTComplex tmp = { *(in2 - 2*k*stride), *(in1 + 2*k*stride) };
             CMUL3(fft15in[j], tmp, s->twiddle_exptab[k]);
         }
-        fft15(s->exptab, s->tmp + s->ptwo_fft.revtab[i], fft15in, l_ptwo);
+        s->fft15(s->tmp + s->ptwo_fft.revtab[i], fft15in, s->exptab, l_ptwo);
     }
 
     /* Then a 15xN FFT (where N is a power of two) */
@@ -327,3 +242,86 @@ static void imdct15_half(MDCT15Context *s, float *dst, const float *src,
         z[i0].im = scale * im1;
     }
 }
+
+av_cold int ff_mdct15_init(MDCT15Context **ps, int inverse, int N, double scale)
+{
+    MDCT15Context *s;
+    double alpha, theta;
+    int len2 = 15 * (1 << N);
+    int len  = 2 * len2;
+    int i;
+
+    /* Tested and verified to work on everything in between */
+    if ((N < 2) || (N > 13))
+        return AVERROR(EINVAL);
+
+    s = av_mallocz(sizeof(*s));
+    if (!s)
+        return AVERROR(ENOMEM);
+
+    s->fft_n      = N - 1;
+    s->len4       = len2 / 2;
+    s->len2       = len2;
+    s->inverse    = inverse;
+    s->fft15      = fft15_c;
+    s->mdct       = mdct15;
+    s->imdct_half = imdct15_half;
+
+    if (ff_fft_init(&s->ptwo_fft, N - 1, s->inverse) < 0)
+        goto fail;
+
+    if (init_pfa_reindex_tabs(s))
+        goto fail;
+
+    s->tmp  = av_malloc_array(len, 2 * sizeof(*s->tmp));
+    if (!s->tmp)
+        goto fail;
+
+    s->twiddle_exptab  = av_malloc_array(s->len4, sizeof(*s->twiddle_exptab));
+    if (!s->twiddle_exptab)
+        goto fail;
+
+    theta = 0.125f + (scale < 0 ? s->len4 : 0);
+    scale = sqrt(fabs(scale));
+    for (i = 0; i < s->len4; i++) {
+        alpha = 2 * M_PI * (i + theta) / len;
+        s->twiddle_exptab[i].re = cosf(alpha) * scale;
+        s->twiddle_exptab[i].im = sinf(alpha) * scale;
+    }
+
+    /* 15-point FFT exptab */
+    for (i = 0; i < 19; i++) {
+        if (i < 15) {
+            double theta = (2.0f * M_PI * i) / 15.0f;
+            if (!s->inverse)
+                theta *= -1;
+            s->exptab[i].re = cosf(theta);
+            s->exptab[i].im = sinf(theta);
+        } else { /* Wrap around to simplify fft15 */
+            s->exptab[i] = s->exptab[i - 15];
+        }
+    }
+
+    /* 5-point FFT exptab */
+    s->exptab[19].re = cosf(2.0f * M_PI / 5.0f);
+    s->exptab[19].im = sinf(2.0f * M_PI / 5.0f);
+    s->exptab[20].re = cosf(1.0f * M_PI / 5.0f);
+    s->exptab[20].im = sinf(1.0f * M_PI / 5.0f);
+
+    /* Invert the phase for an inverse transform, do nothing for a forward transform */
+    if (s->inverse) {
+        s->exptab[19].im *= -1;
+        s->exptab[20].im *= -1;
+    }
+
+    if (ARCH_X86)
+        ff_mdct15_init_x86(s);
+
+    *ps = s;
+
+    return 0;
+
+fail:
+    ff_mdct15_uninit(&s);
+    return AVERROR(ENOMEM);
+}
diff --git a/libavcodec/mdct15.h b/libavcodec/mdct15.h
index ef94edff6c..7d83f3ebdf 100644
--- a/libavcodec/mdct15.h
+++ b/libavcodec/mdct15.h
@@ -34,34 +34,26 @@ typedef struct MDCT15Context {
     int *pfa_postreindex;
 
     FFTContext ptwo_fft;
-
     FFTComplex *tmp;
-
     FFTComplex *twiddle_exptab;
 
-    /* 0 - 18: fft15 twiddles, 19 - 20: fft5 twiddles */
-    FFTComplex exptab[21];
+    DECLARE_ALIGNED(32, FFTComplex, exptab)[64];
 
-    /**
-     * Calculate a full 2N -> N MDCT
-     */
+    /* 15-point FFT */
+    void (*fft15)(FFTComplex *out, FFTComplex *in, FFTComplex *exptab, ptrdiff_t stride);
+
+    /* Calculate a full 2N -> N MDCT */
     void (*mdct)(struct MDCT15Context *s, float *dst, const float *src, ptrdiff_t stride);
 
-    /**
-     * Calculate the middle half of the iMDCT
-     */
+    /* Calculate the middle half of the iMDCT */
     void (*imdct_half)(struct MDCT15Context *s, float *dst, const float *src,
                        ptrdiff_t src_stride, float scale);
 } MDCT15Context;
 
-/**
- * Init an (i)MDCT of the length 2 * 15 * (2^N)
- */
+/* Init an (i)MDCT of the length 2 * 15 * (2^N) */
 int ff_mdct15_init(MDCT15Context **ps, int inverse, int N, double scale);
-
-/**
- * Frees a context
- */
 void ff_mdct15_uninit(MDCT15Context **ps);
 
+void ff_mdct15_init_x86(MDCT15Context *s);
+
 #endif /* AVCODEC_MDCT15_H */
diff --git a/libavcodec/x86/Makefile b/libavcodec/x86/Makefile
index e65118d134..b86700b675 100644
--- a/libavcodec/x86/Makefile
+++ b/libavcodec/x86/Makefile
@@ -25,6 +25,7 @@ OBJS-$(CONFIG_HUFFYUVDSP)              += x86/huffyuvdsp_init.o
 OBJS-$(CONFIG_HUFFYUVENCDSP)           += x86/huffyuvencdsp_init.o
 OBJS-$(CONFIG_IDCTDSP)                 += x86/idctdsp_init.o
 OBJS-$(CONFIG_LPC)                     += x86/lpc.o
+OBJS-$(CONFIG_MDCT15)                  += x86/mdct15_init.o
 OBJS-$(CONFIG_ME_CMP)                  += x86/me_cmp_init.o
 OBJS-$(CONFIG_MPEGAUDIODSP)            += x86/mpegaudiodsp.o
 OBJS-$(CONFIG_MPEGVIDEO)               += x86/mpegvideo.o              \
@@ -117,6 +118,7 @@ X86ASM-OBJS-$(CONFIG_IDCTDSP)          += x86/idctdsp.o
 X86ASM-OBJS-$(CONFIG_LLAUDDSP)         += x86/lossless_audiodsp.o
 X86ASM-OBJS-$(CONFIG_LLVIDDSP)         += x86/lossless_videodsp.o
 X86ASM-OBJS-$(CONFIG_LLVIDENCDSP)      += x86/lossless_videoencdsp.o
+X86ASM-OBJS-$(CONFIG_MDCT15)           += x86/mdct15.o
 X86ASM-OBJS-$(CONFIG_ME_CMP)           += x86/me_cmp.o
 X86ASM-OBJS-$(CONFIG_MPEGAUDIODSP)     += x86/imdct36.o
 X86ASM-OBJS-$(CONFIG_MPEGVIDEOENC)     += x86/mpegvideoencdsp.o
diff --git a/libavcodec/x86/mdct15.asm b/libavcodec/x86/mdct15.asm
new file mode 100644
index 0000000000..8d01675956
--- /dev/null
+++ b/libavcodec/x86/mdct15.asm
@@ -0,0 +1,141 @@
+;******************************************************************************
+;* SIMD optimized non-power-of-two MDCT functions
+;*
+;* Copyright (C) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
+;*
+;* This file is part of FFmpeg.
+;*
+;* FFmpeg is free software; you can redistribute it and/or
+;* modify it under the terms of the GNU Lesser General Public
+;* License as published by the Free Software Foundation; either
+;* version 2.1 of the License, or (at your option) any later version.
+;*
+;* FFmpeg is distributed in the hope that it will be useful,
+;* but WITHOUT ANY WARRANTY; without even the implied warranty of
+;* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+;* Lesser General Public License for more details.
+;*
+;* You should have received a copy of the GNU Lesser General Public
+;* License along with FFmpeg; if not, write to the Free Software
+;* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+;******************************************************************************
+
+%include "libavutil/x86/x86util.asm"
+
+%if ARCH_X86_64
+
+SECTION_RODATA
+
+sign_adjust_5: dd 0x00000000, 0x80000000, 0x80000000, 0x00000000
+
+SECTION .text
+
+%macro FFT5 3 ; %1 - in_offset, %2 - dst1 (64bit used), %3 - dst2
+    VBROADCASTSD m0, [inq + %1]         ; in[ 0].re, in[ 0].im, in[ 0].re, in[ 0].im
+    movsd   xm1, [inq + 1*16 +  8 + %1] ; in[ 3].re, in[ 3].im,         0,         0
+    movsd   xm4, [inq + 6*16 +  0 + %1] ; in[12].re, in[12].im,         0,         0
+    movhps  xm1, [inq + 3*16 +  0 + %1] ; in[ 3].re, in[ 3].im, in[ 6].re, in[ 6].im
+    movhps  xm4, [inq + 4*16 +  8 + %1] ; in[12].re, in[12].im, in[ 9].re, in[ 9].im
+
+    subps       xm2,  xm1, xm4          ; t[2].im, t[2].re, t[3].im, t[3].re
+    addps       xm1,  xm4               ; t[0].re, t[0].im, t[1].re, t[1].im
+
+    movhlps     %2,   xm1               ; t[0].re, t[1].re, t[0].im, t[1].im
+    addps       %2,   xm1
+    addps       %2,   xm0               ; DC[0].re, DC[0].im, junk...
+    movlhps     %2,   %2                ; DC[0].re, DC[0].im, DC[0].re, DC[0].im
+
+    shufps      xm3,  xm1, xm2, q0110   ; t[0].re, t[0].im, t[2].re, t[2].im
+    shufps      xm1,  xm2, q2332        ; t[1].re, t[1].im, t[3].re, t[3].im
+
+    mulps       xm%3, xm1, xm5
+    mulps       xm4,  xm3, xm6
+    mulps       xm1,  xm6
+
+    xorps       xm1,  xm7
+    mulps       xm3,  xm5
+    addsubps    xm3,  xm1               ; t[0].re, t[0].im, t[2].re, t[2].im
+    subps       xm%3, xm4               ; t[4].re, t[4].im, t[5].re, t[5].im
+
+    movhlps     xm2, xm%3, xm3          ; t[2].re, t[2].im, t[5].re, t[5].im
+    movlhps     xm3, xm%3               ; t[0].re, t[0].im, t[4].re, t[4].im
+
+    xorps       xm2,  xm7
+    addps       xm%3, xm2, xm3
+    subps       xm3,  xm2
+
+    shufps      xm3,  xm3, q1032
+    vinsertf128 m%3,  m%3, xm3, 1       ; All ACs (tmp[1] through to tmp[4])
+    addps       m%3,  m0                ; Finally offset with DCs
+%endmacro
+
+%macro BUTTERFLIES_DC 2 ; %1 - exptab_offset, %2 - out
+    mulps xm0,  xm9, [exptabq + %1 + 16*0]
+    mulps xm1, xm10, [exptabq + %1 + 16*1]
+
+    haddps  xm0,  xm1
+    movhlps xm1,  xm0                   ; t[0].re, t[1].re, t[0].im, t[1].im
+
+    addps   xm0,  xm1
+    addps   xm0,  xm8
+
+    movsd [%2q], xm0
+%endmacro
+
+%macro BUTTERFLIES_AC 2 ; exptab, exptab_offset, src1, src2, src3, out (uses m0-m3)
+    mulps  m0, m12, [exptabq + 64*0 + 0*mmsize + %1]
+    mulps  m1, m12, [exptabq + 64*0 + 1*mmsize + %1]
+    mulps  m2, m13, [exptabq + 64*1 + 0*mmsize + %1]
+    mulps  m3, m13, [exptabq + 64*1 + 1*mmsize + %1]
+
+    addps  m0, m2
+    addps  m1, m3
+    addps  m0, m11
+
+    shufps m1, m1, q2301
+    addps  m0, m1
+
+    vextractf128 xm1, m0, 1
+
+    movlps [%2q + strideq*1], xm0
+    movhps [%2q + strideq*2], xm0
+    movlps [%2q +  stride3q], xm1
+    movhps [%2q + strideq*4], xm1
+%endmacro
+
+;*****************************************************************************************
+;void ff_fft15_avx(FFTComplex *out, FFTComplex *in, FFTComplex *exptab, ptrdiff_t stride);
+;*****************************************************************************************
+INIT_YMM avx
+cglobal fft15, 4, 6, 14, out, in, exptab, stride, stride3, stride5
+%define out0q inq
+    shl strideq, 3
+
+    movaps xm5, [exptabq + 480 + 16*0]
+    movaps xm6, [exptabq + 480 + 16*1]
+    movaps xm7, [sign_adjust_5]
+
+    FFT5  0,  xm8, 11
+    FFT5  8,  xm9, 12
+    FFT5 16, xm10, 13
+
+    lea stride3q, [strideq + strideq*2]
+    lea stride5q, [strideq + strideq*4]
+
+    mov out0q, outq
+
+    BUTTERFLIES_DC (8*6 + 4*0)*2*4, out0
+    lea outq, [out0q + stride5q*1]
+    BUTTERFLIES_DC (8*6 + 4*1)*2*4, out
+    lea outq, [out0q + stride5q*2]
+    BUTTERFLIES_DC (8*6 + 4*2)*2*4, out
+
+    BUTTERFLIES_AC (8*0)*2*4, out0
+    lea outq, [out0q + stride5q*1]
+    BUTTERFLIES_AC (8*2)*2*4, out
+    lea outq, [out0q + stride5q*2]
+    BUTTERFLIES_AC (8*4)*2*4, out
+
+    RET
+
+%endif
diff --git a/libavcodec/x86/mdct15_init.c b/libavcodec/x86/mdct15_init.c
new file mode 100644
index 0000000000..ba3d94c2ec
--- /dev/null
+++ b/libavcodec/x86/mdct15_init.c
@@ -0,0 +1,95 @@
+/*
+ * SIMD optimized non-power-of-two MDCT functions
+ *
+ * Copyright (C) 2017 Rostislav Pehlivanov <atomnuker@gmail.com>
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "config.h"
+
+#include "libavutil/x86/cpu.h"
+#include "libavcodec/mdct15.h"
+
+void ff_fft15_avx(FFTComplex *out, FFTComplex *in, FFTComplex *exptab, ptrdiff_t stride);
+
+static void perm_twiddles(MDCT15Context *s)
+{
+    int k;
+    FFTComplex exp_5point[4];
+
+    FFTComplex tmp[21], tmp2[30];
+    memcpy(tmp, s->exptab, sizeof(FFTComplex)*21);
+
+    /* 15-point FFT twiddles */
+    for (k = 0; k < 5; k++) {
+        tmp2[6*k + 0] = tmp[k +  0];
+        tmp2[6*k + 2] = tmp[k +  5];
+        tmp2[6*k + 4] = tmp[k + 10];
+
+        tmp2[6*k + 1] = tmp[2 * (k + 0)];
+        tmp2[6*k + 3] = tmp[2 * (k + 5)];
+        tmp2[6*k + 5] = tmp[2 *  k + 5 ];
+    }
+
+    for (k = 0; k < 6; k++) {
+        FFTComplex ac_exp[] = {
+            { tmp2[6*1 + k].re,  tmp2[6*1 + k].re },
+            { tmp2[6*2 + k].re,  tmp2[6*2 + k].re },
+            { tmp2[6*3 + k].re,  tmp2[6*3 + k].re },
+            { tmp2[6*4 + k].re,  tmp2[6*4 + k].re },
+            { tmp2[6*1 + k].im, -tmp2[6*1 + k].im },
+            { tmp2[6*2 + k].im, -tmp2[6*2 + k].im },
+            { tmp2[6*3 + k].im, -tmp2[6*3 + k].im },
+            { tmp2[6*4 + k].im, -tmp2[6*4 + k].im },
+        };
+        memcpy(s->exptab + 8*k, ac_exp, 8*sizeof(FFTComplex));
+    }
+
+    /* Specialcase when k = 0 */
+    for (k = 0; k < 3; k++) {
+        FFTComplex dc_exp[] = {
+            { tmp2[2*k + 0].re, -tmp2[2*k + 0].im },
+            { tmp2[2*k + 0].im,  tmp2[2*k + 0].re },
+            { tmp2[2*k + 1].re, -tmp2[2*k + 1].im },
+            { tmp2[2*k + 1].im,  tmp2[2*k + 1].re },
+        };
+        memcpy(s->exptab + 8*6 + 4*k, dc_exp, 4*sizeof(FFTComplex));
+    }
+
+    /* 5-point FFT twiddles */
+    exp_5point[0].re = exp_5point[0].im = tmp[19].re;
+    exp_5point[1].re = exp_5point[1].im = tmp[19].im;
+    exp_5point[2].re = exp_5point[2].im = tmp[20].re;
+    exp_5point[3].re = exp_5point[3].im = tmp[20].im;
+
+    memcpy(s->exptab + 8*6 + 4*3, exp_5point, 4*sizeof(FFTComplex));
+}
+
+av_cold void ff_mdct15_init_x86(MDCT15Context *s)
+{
+    int adjust_twiddles = 0;
+    int cpu_flags = av_get_cpu_flags();
+
+    if (ARCH_X86_64 && EXTERNAL_AVX(cpu_flags)) {
+        s->fft15 = ff_fft15_avx;
+        adjust_twiddles = 1;
+    }
+
+    if (adjust_twiddles)
+        perm_twiddles(s);
+}