mpegaudiodec: move imdct and windowing function to mpegaudiodsp

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

4 files changed, 226 insertions, 178 deletions

diff --git a/libavcodec/mpegaudiodec.c b/libavcodec/mpegaudiodec.c
index 702476b7ec..70c5f76381 100644
--- a/libavcodec/mpegaudiodec.c
+++ b/libavcodec/mpegaudiodec.c
@@ -130,7 +130,6 @@ static uint16_t band_index_long[9][23];
 static INTFLOAT is_table[2][16];
 static INTFLOAT is_table_lsf[2][2][16];
 static INTFLOAT csa_table[8][4];
-static INTFLOAT mdct_win[8][36];
 
 static int16_t division_tab3[1<<6 ];
 static int16_t division_tab5[1<<8 ];
@@ -417,43 +416,6 @@ static av_cold void decode_init_static(void)
         csa_table[i][3] = ca - cs;
 #endif
     }
-
-    /* compute mdct windows */
-    for (i = 0; i < 36; i++) {
-        for (j = 0; j < 4; j++) {
-            double d;
-
-            if (j == 2 && i % 3 != 1)
-                continue;
-
-            d = sin(M_PI * (i + 0.5) / 36.0);
-            if (j == 1) {
-                if      (i >= 30) d = 0;
-                else if (i >= 24) d = sin(M_PI * (i - 18 + 0.5) / 12.0);
-                else if (i >= 18) d = 1;
-            } else if (j == 3) {
-                if      (i <   6) d = 0;
-                else if (i <  12) d = sin(M_PI * (i -  6 + 0.5) / 12.0);
-                else if (i <  18) d = 1;
-            }
-            //merge last stage of imdct into the window coefficients
-            d *= 0.5 / cos(M_PI * (2 * i + 19) / 72);
-
-            if (j == 2)
-                mdct_win[j][i/3] = FIXHR((d / (1<<5)));
-            else
-                mdct_win[j][i  ] = FIXHR((d / (1<<5)));
-        }
-    }
-
-    /* NOTE: we do frequency inversion adter the MDCT by changing
-        the sign of the right window coefs */
-    for (j = 0; j < 4; j++) {
-        for (i = 0; i < 36; i += 2) {
-            mdct_win[j + 4][i    ] =  mdct_win[j][i    ];
-            mdct_win[j + 4][i + 1] = -mdct_win[j][i + 1];
-        }
-    }
 }
 
 static av_cold int decode_init(AVCodecContext * avctx)
@@ -483,32 +445,9 @@ static av_cold int decode_init(AVCodecContext * avctx)
 }
 
 #define C3 FIXHR(0.86602540378443864676/2)
-
-/* 0.5 / cos(pi*(2*i+1)/36) */
-static const INTFLOAT icos36[9] = {
-    FIXR(0.50190991877167369479),
-    FIXR(0.51763809020504152469), //0
-    FIXR(0.55168895948124587824),
-    FIXR(0.61038729438072803416),
-    FIXR(0.70710678118654752439), //1
-    FIXR(0.87172339781054900991),
-    FIXR(1.18310079157624925896),
-    FIXR(1.93185165257813657349), //2
-    FIXR(5.73685662283492756461),
-};
-
-/* 0.5 / cos(pi*(2*i+1)/36) */
-static const INTFLOAT icos36h[9] = {
-    FIXHR(0.50190991877167369479/2),
-    FIXHR(0.51763809020504152469/2), //0
-    FIXHR(0.55168895948124587824/2),
-    FIXHR(0.61038729438072803416/2),
-    FIXHR(0.70710678118654752439/2), //1
-    FIXHR(0.87172339781054900991/2),
-    FIXHR(1.18310079157624925896/4),
-    FIXHR(1.93185165257813657349/4), //2
-//    FIXHR(5.73685662283492756461),
-};
+#define C4 FIXHR(0.70710678118654752439/2) //0.5 / cos(pi*(9)/36)
+#define C5 FIXHR(0.51763809020504152469/2) //0.5 / cos(pi*(5)/36)
+#define C6 FIXHR(1.93185165257813657349/4) //0.5 / cos(pi*(15)/36)
 
 /* 12 points IMDCT. We compute it "by hand" by factorizing obvious
    cases. */
@@ -529,7 +468,7 @@ static void imdct12(INTFLOAT *out, INTFLOAT *in)
     in3  = MULH3(in3, C3, 4);
 
     t1   = in0 - in4;
-    t2   = MULH3(in1 - in5, icos36h[4], 2);
+    t2   = MULH3(in1 - in5, C4, 2);
 
     out[ 7] =
     out[10] = t1 + t2;
@@ -539,112 +478,20 @@ static void imdct12(INTFLOAT *out, INTFLOAT *in)
     in0    += SHR(in4, 1);
     in4     = in0 + in2;
     in5    += 2*in1;
-    in1     = MULH3(in5 + in3, icos36h[1], 1);
+    in1     = MULH3(in5 + in3, C5, 1);
     out[ 8] =
     out[ 9] = in4 + in1;
     out[ 2] =
     out[ 3] = in4 - in1;
 
     in0    -= in2;
-    in5     = MULH3(in5 - in3, icos36h[7], 2);
+    in5     = MULH3(in5 - in3, C6, 2);
     out[ 0] =
     out[ 5] = in0 - in5;
     out[ 6] =
     out[11] = in0 + in5;
 }
 
-/* cos(pi*i/18) */
-#define C1 FIXHR(0.98480775301220805936/2)
-#define C2 FIXHR(0.93969262078590838405/2)
-#define C3 FIXHR(0.86602540378443864676/2)
-#define C4 FIXHR(0.76604444311897803520/2)
-#define C5 FIXHR(0.64278760968653932632/2)
-#define C6 FIXHR(0.5/2)
-#define C7 FIXHR(0.34202014332566873304/2)
-#define C8 FIXHR(0.17364817766693034885/2)
-
-
-/* using Lee like decomposition followed by hand coded 9 points DCT */
-static void imdct36(INTFLOAT *out, INTFLOAT *buf, INTFLOAT *in, INTFLOAT *win)
-{
-    int i, j;
-    INTFLOAT t0, t1, t2, t3, s0, s1, s2, s3;
-    INTFLOAT tmp[18], *tmp1, *in1;
-
-    for (i = 17; i >= 1; i--)
-        in[i] += in[i-1];
-    for (i = 17; i >= 3; i -= 2)
-        in[i] += in[i-2];
-
-    for (j = 0; j < 2; j++) {
-        tmp1 = tmp + j;
-        in1 = in + j;
-
-        t2 = in1[2*4] + in1[2*8] - in1[2*2];
-
-        t3 = in1[2*0] + SHR(in1[2*6],1);
-        t1 = in1[2*0] - in1[2*6];
-        tmp1[ 6] = t1 - SHR(t2,1);
-        tmp1[16] = t1 + t2;
-
-        t0 = MULH3(in1[2*2] + in1[2*4] ,    C2, 2);
-        t1 = MULH3(in1[2*4] - in1[2*8] , -2*C8, 1);
-        t2 = MULH3(in1[2*2] + in1[2*8] ,   -C4, 2);
-
-        tmp1[10] = t3 - t0 - t2;
-        tmp1[ 2] = t3 + t0 + t1;
-        tmp1[14] = t3 + t2 - t1;
-
-        tmp1[ 4] = MULH3(in1[2*5] + in1[2*7] - in1[2*1], -C3, 2);
-        t2 = MULH3(in1[2*1] + in1[2*5],    C1, 2);
-        t3 = MULH3(in1[2*5] - in1[2*7], -2*C7, 1);
-        t0 = MULH3(in1[2*3], C3, 2);
-
-        t1 = MULH3(in1[2*1] + in1[2*7],   -C5, 2);
-
-        tmp1[ 0] = t2 + t3 + t0;
-        tmp1[12] = t2 + t1 - t0;
-        tmp1[ 8] = t3 - t1 - t0;
-    }
-
-    i = 0;
-    for (j = 0; j < 4; j++) {
-        t0 = tmp[i];
-        t1 = tmp[i + 2];
-        s0 = t1 + t0;
-        s2 = t1 - t0;
-
-        t2 = tmp[i + 1];
-        t3 = tmp[i + 3];
-        s1 = MULH3(t3 + t2, icos36h[    j], 2);
-        s3 = MULLx(t3 - t2, icos36 [8 - j], FRAC_BITS);
-
-        t0 = s0 + s1;
-        t1 = s0 - s1;
-        out[(9 + j) * SBLIMIT] = MULH3(t1, win[     9 + j], 1) + buf[4*(9 + j)];
-        out[(8 - j) * SBLIMIT] = MULH3(t1, win[     8 - j], 1) + buf[4*(8 - j)];
-        buf[4 * ( 9 + j     )] = MULH3(t0, win[18 + 9 + j], 1);
-        buf[4 * ( 8 - j     )] = MULH3(t0, win[18 + 8 - j], 1);
-
-        t0 = s2 + s3;
-        t1 = s2 - s3;
-        out[(9 + 8 - j) * SBLIMIT] = MULH3(t1, win[     9 + 8 - j], 1) + buf[4*(9 + 8 - j)];
-        out[         j  * SBLIMIT] = MULH3(t1, win[             j], 1) + buf[4*(        j)];
-        buf[4 * ( 9 + 8 - j     )] = MULH3(t0, win[18 + 9 + 8 - j], 1);
-        buf[4 * (         j     )] = MULH3(t0, win[18         + j], 1);
-        i += 4;
-    }
-
-    s0 = tmp[16];
-    s1 = MULH3(tmp[17], icos36h[4], 2);
-    t0 = s0 + s1;
-    t1 = s0 - s1;
-    out[(9 + 4) * SBLIMIT] = MULH3(t1, win[     9 + 4], 1) + buf[4*(9 + 4)];
-    out[(8 - 4) * SBLIMIT] = MULH3(t1, win[     8 - 4], 1) + buf[4*(8 - 4)];
-    buf[4 * ( 9 + 4     )] = MULH3(t0, win[18 + 9 + 4], 1);
-    buf[4 * ( 8 - 4     )] = MULH3(t0, win[18 + 8 - 4], 1);
-}
-
 /* return the number of decoded frames */
 static int mp_decode_layer1(MPADecodeContext *s)
 {
@@ -1366,7 +1213,7 @@ static void compute_antialias(MPADecodeContext *s, GranuleDef *g)
 static void compute_imdct(MPADecodeContext *s, GranuleDef *g,
                           INTFLOAT *sb_samples, INTFLOAT *mdct_buf)
 {
-    INTFLOAT *win, *win1, *out_ptr, *ptr, *buf, *ptr1;
+    INTFLOAT *win, *out_ptr, *ptr, *buf, *ptr1;
     INTFLOAT out2[12];
     int i, j, mdct_long_end, sblimit;
 
@@ -1392,26 +1239,16 @@ static void compute_imdct(MPADecodeContext *s, GranuleDef *g,
         mdct_long_end = sblimit;
     }
 
-    buf = mdct_buf;
-    ptr = g->sb_hybrid;
-    for (j = 0; j < mdct_long_end; j++) {
-        /* apply window & overlap with previous buffer */
-        out_ptr = sb_samples + j;
-        /* select window */
-        if (g->switch_point && j < 2)
-            win1 = mdct_win[0];
-        else
-            win1 = mdct_win[g->block_type];
-        /* select frequency inversion */
-        win = win1 + ((4 * 36) & -(j & 1));
-        imdct36(out_ptr, buf, ptr, win);
-        out_ptr += 18 * SBLIMIT;
-        ptr     += 18;
-        buf     += (j&3) != 3 ? 1 : (4*18-3);
-    }
+    s->mpadsp.RENAME(imdct36_blocks)(sb_samples, mdct_buf, g->sb_hybrid,
+                                     mdct_long_end, g->switch_point,
+                                     g->block_type);
+
+    buf = mdct_buf + 4*18*(mdct_long_end >> 2) + (mdct_long_end & 3);
+    ptr = g->sb_hybrid + 18 * mdct_long_end;
+
     for (j = mdct_long_end; j < sblimit; j++) {
         /* select frequency inversion */
-        win     = mdct_win[2 + (4  & -(j & 1))];
+        win     = RENAME(ff_mdct_win)[2 + (4  & -(j & 1))];
         out_ptr = sb_samples + j;
 
         for (i = 0; i < 6; i++) {
diff --git a/libavcodec/mpegaudiodsp.c b/libavcodec/mpegaudiodsp.c
index 438b097d06..431724a71c 100644
--- a/libavcodec/mpegaudiodsp.c
+++ b/libavcodec/mpegaudiodsp.c
@@ -28,6 +28,8 @@ void ff_mpadsp_init(MPADSPContext *s)
     DCTContext dct;
 
     ff_dct_init(&dct, 5, DCT_II);
+    ff_init_mpadsp_tabs_float();
+    ff_init_mpadsp_tabs_fixed();
 
     s->apply_window_float = ff_mpadsp_apply_window_float;
     s->apply_window_fixed = ff_mpadsp_apply_window_fixed;
@@ -35,6 +37,9 @@ void ff_mpadsp_init(MPADSPContext *s)
     s->dct32_float = dct.dct32;
     s->dct32_fixed = ff_dct32_fixed;
 
+    s->imdct36_blocks_float = ff_imdct36_blocks_float;
+    s->imdct36_blocks_fixed = ff_imdct36_blocks_fixed;
+
     if (ARCH_ARM)     ff_mpadsp_init_arm(s);
     if (HAVE_MMX)     ff_mpadsp_init_mmx(s);
     if (HAVE_ALTIVEC) ff_mpadsp_init_altivec(s);
diff --git a/libavcodec/mpegaudiodsp.h b/libavcodec/mpegaudiodsp.h
index 8a18db8325..01fd698f3e 100644
--- a/libavcodec/mpegaudiodsp.h
+++ b/libavcodec/mpegaudiodsp.h
@@ -28,6 +28,10 @@ typedef struct MPADSPContext {
                                int *dither_state, int16_t *samples, int incr);
     void (*dct32_float)(float *dst, const float *src);
     void (*dct32_fixed)(int *dst, const int *src);
+    void (*imdct36_blocks_float)(float *out, float *buf, float *in,
+                                 int count, int switch_point, int block_type);
+    void (*imdct36_blocks_fixed)(int *out, int *buf, int *in,
+                                 int count, int switch_point, int block_type);
 } MPADSPContext;
 
 void ff_mpadsp_init(MPADSPContext *s);
@@ -61,4 +65,16 @@ void ff_mpadsp_apply_window_fixed(int32_t *synth_buf, int32_t *window,
                                   int *dither_state, int16_t *samples,
                                   int incr);
 
+void ff_imdct36_blocks_float(float *out, float *buf, float *in,
+                             int count, int switch_point, int block_type);
+
+void ff_imdct36_blocks_fixed(int *out, int *buf, int *in,
+                             int count, int switch_point, int block_type);
+
+void ff_init_mpadsp_tabs_float(void);
+void ff_init_mpadsp_tabs_fixed(void);
+
+extern int ff_mdct_win_fixed[8][36];
+extern float ff_mdct_win_float[8][36];
+
 #endif /* AVCODEC_MPEGAUDIODSP_H */
diff --git a/libavcodec/mpegaudiodsp_template.c b/libavcodec/mpegaudiodsp_template.c
index 5561c46135..5a6adb8cca 100644
--- a/libavcodec/mpegaudiodsp_template.c
+++ b/libavcodec/mpegaudiodsp_template.c
@@ -39,7 +39,12 @@ static inline float round_sample(float *sum)
 
 #define MACS(rt, ra, rb) rt+=(ra)*(rb)
 #define MULS(ra, rb) ((ra)*(rb))
+#define MULH3(x, y, s) ((s)*(y)*(x))
 #define MLSS(rt, ra, rb) rt-=(ra)*(rb)
+#define MULLx(x, y, s) ((y)*(x))
+#define FIXHR(x)        ((float)(x))
+#define FIXR(x)        ((float)(x))
+#define SHR(a,b)       ((a)*(1.0f/(1<<(b))))
 
 #else
 
@@ -57,8 +62,16 @@ static inline int round_sample(int64_t *sum)
 #   define MULS(ra, rb) MUL64(ra, rb)
 #   define MACS(rt, ra, rb) MAC64(rt, ra, rb)
 #   define MLSS(rt, ra, rb) MLS64(rt, ra, rb)
+#   define MULH3(x, y, s) MULH((s)*(x), y)
+#   define MULLx(x, y, s) MULL(x,y,s)
+#   define SHR(a,b)       ((a)>>(b))
+#   define FIXR(a)        ((int)((a) * FRAC_ONE + 0.5))
+#   define FIXHR(a)       ((int)((a) * (1LL<<32) + 0.5))
 #endif
 
+/** Window for MDCT. */
+DECLARE_ALIGNED(16, INTFLOAT, RENAME(ff_mdct_win))[8][36];
+
 DECLARE_ALIGNED(16, MPA_INT, RENAME(ff_mpa_synth_window))[512+256];
 
 #define SUM8(op, sum, w, p)               \
@@ -194,6 +207,7 @@ void av_cold RENAME(ff_mpa_synth_init)(MPA_INT *window)
             window[512 - i] = v;
     }
 
+
     // Needed for avoiding shuffles in ASM implementations
     for(i=0; i < 8; i++)
         for(j=0; j < 16; j++)
@@ -203,3 +217,179 @@ void av_cold RENAME(ff_mpa_synth_init)(MPA_INT *window)
         for(j=0; j < 16; j++)
             window[512+128+16*i+j] = window[64*i+48-j];
 }
+
+void RENAME(ff_init_mpadsp_tabs)(void)
+{
+    int i, j;
+    /* compute mdct windows */
+    for (i = 0; i < 36; i++) {
+        for (j = 0; j < 4; j++) {
+            double d;
+
+            if (j == 2 && i % 3 != 1)
+                continue;
+
+            d = sin(M_PI * (i + 0.5) / 36.0);
+            if (j == 1) {
+                if      (i >= 30) d = 0;
+                else if (i >= 24) d = sin(M_PI * (i - 18 + 0.5) / 12.0);
+                else if (i >= 18) d = 1;
+            } else if (j == 3) {
+                if      (i <   6) d = 0;
+                else if (i <  12) d = sin(M_PI * (i -  6 + 0.5) / 12.0);
+                else if (i <  18) d = 1;
+            }
+            //merge last stage of imdct into the window coefficients
+            d *= 0.5 / cos(M_PI * (2 * i + 19) / 72);
+
+            if (j == 2)
+                RENAME(ff_mdct_win)[j][i/3] = FIXHR((d / (1<<5)));
+            else
+                RENAME(ff_mdct_win)[j][i  ] = FIXHR((d / (1<<5)));
+        }
+    }
+
+    /* NOTE: we do frequency inversion adter the MDCT by changing
+        the sign of the right window coefs */
+    for (j = 0; j < 4; j++) {
+        for (i = 0; i < 36; i += 2) {
+            RENAME(ff_mdct_win)[j + 4][i    ] =  RENAME(ff_mdct_win)[j][i    ];
+            RENAME(ff_mdct_win)[j + 4][i + 1] = -RENAME(ff_mdct_win)[j][i + 1];
+        }
+    }
+}
+/* cos(pi*i/18) */
+#define C1 FIXHR(0.98480775301220805936/2)
+#define C2 FIXHR(0.93969262078590838405/2)
+#define C3 FIXHR(0.86602540378443864676/2)
+#define C4 FIXHR(0.76604444311897803520/2)
+#define C5 FIXHR(0.64278760968653932632/2)
+#define C6 FIXHR(0.5/2)
+#define C7 FIXHR(0.34202014332566873304/2)
+#define C8 FIXHR(0.17364817766693034885/2)
+
+/* 0.5 / cos(pi*(2*i+1)/36) */
+static const INTFLOAT icos36[9] = {
+    FIXR(0.50190991877167369479),
+    FIXR(0.51763809020504152469), //0
+    FIXR(0.55168895948124587824),
+    FIXR(0.61038729438072803416),
+    FIXR(0.70710678118654752439), //1
+    FIXR(0.87172339781054900991),
+    FIXR(1.18310079157624925896),
+    FIXR(1.93185165257813657349), //2
+    FIXR(5.73685662283492756461),
+};
+
+/* 0.5 / cos(pi*(2*i+1)/36) */
+static const INTFLOAT icos36h[9] = {
+    FIXHR(0.50190991877167369479/2),
+    FIXHR(0.51763809020504152469/2), //0
+    FIXHR(0.55168895948124587824/2),
+    FIXHR(0.61038729438072803416/2),
+    FIXHR(0.70710678118654752439/2), //1
+    FIXHR(0.87172339781054900991/2),
+    FIXHR(1.18310079157624925896/4),
+    FIXHR(1.93185165257813657349/4), //2
+//    FIXHR(5.73685662283492756461),
+};
+
+/* using Lee like decomposition followed by hand coded 9 points DCT */
+static void imdct36(INTFLOAT *out, INTFLOAT *buf, INTFLOAT *in, INTFLOAT *win)
+{
+    int i, j;
+    INTFLOAT t0, t1, t2, t3, s0, s1, s2, s3;
+    INTFLOAT tmp[18], *tmp1, *in1;
+
+    for (i = 17; i >= 1; i--)
+        in[i] += in[i-1];
+    for (i = 17; i >= 3; i -= 2)
+        in[i] += in[i-2];
+
+    for (j = 0; j < 2; j++) {
+        tmp1 = tmp + j;
+        in1 = in + j;
+
+        t2 = in1[2*4] + in1[2*8] - in1[2*2];
+
+        t3 = in1[2*0] + SHR(in1[2*6],1);
+        t1 = in1[2*0] - in1[2*6];
+        tmp1[ 6] = t1 - SHR(t2,1);
+        tmp1[16] = t1 + t2;
+
+        t0 = MULH3(in1[2*2] + in1[2*4] ,    C2, 2);
+        t1 = MULH3(in1[2*4] - in1[2*8] , -2*C8, 1);
+        t2 = MULH3(in1[2*2] + in1[2*8] ,   -C4, 2);
+
+        tmp1[10] = t3 - t0 - t2;
+        tmp1[ 2] = t3 + t0 + t1;
+        tmp1[14] = t3 + t2 - t1;
+
+        tmp1[ 4] = MULH3(in1[2*5] + in1[2*7] - in1[2*1], -C3, 2);
+        t2 = MULH3(in1[2*1] + in1[2*5],    C1, 2);
+        t3 = MULH3(in1[2*5] - in1[2*7], -2*C7, 1);
+        t0 = MULH3(in1[2*3], C3, 2);
+
+        t1 = MULH3(in1[2*1] + in1[2*7],   -C5, 2);
+
+        tmp1[ 0] = t2 + t3 + t0;
+        tmp1[12] = t2 + t1 - t0;
+        tmp1[ 8] = t3 - t1 - t0;
+    }
+
+    i = 0;
+    for (j = 0; j < 4; j++) {
+        t0 = tmp[i];
+        t1 = tmp[i + 2];
+        s0 = t1 + t0;
+        s2 = t1 - t0;
+
+        t2 = tmp[i + 1];
+        t3 = tmp[i + 3];
+        s1 = MULH3(t3 + t2, icos36h[    j], 2);
+        s3 = MULLx(t3 - t2, icos36 [8 - j], FRAC_BITS);
+
+        t0 = s0 + s1;
+        t1 = s0 - s1;
+        out[(9 + j) * SBLIMIT] = MULH3(t1, win[     9 + j], 1) + buf[4*(9 + j)];
+        out[(8 - j) * SBLIMIT] = MULH3(t1, win[     8 - j], 1) + buf[4*(8 - j)];
+        buf[4 * ( 9 + j     )] = MULH3(t0, win[18 + 9 + j], 1);
+        buf[4 * ( 8 - j     )] = MULH3(t0, win[18 + 8 - j], 1);
+
+        t0 = s2 + s3;
+        t1 = s2 - s3;
+        out[(9 + 8 - j) * SBLIMIT] = MULH3(t1, win[     9 + 8 - j], 1) + buf[4*(9 + 8 - j)];
+        out[         j  * SBLIMIT] = MULH3(t1, win[             j], 1) + buf[4*(        j)];
+        buf[4 * ( 9 + 8 - j     )] = MULH3(t0, win[18 + 9 + 8 - j], 1);
+        buf[4 * (         j     )] = MULH3(t0, win[18         + j], 1);
+        i += 4;
+    }
+
+    s0 = tmp[16];
+    s1 = MULH3(tmp[17], icos36h[4], 2);
+    t0 = s0 + s1;
+    t1 = s0 - s1;
+    out[(9 + 4) * SBLIMIT] = MULH3(t1, win[     9 + 4], 1) + buf[4*(9 + 4)];
+    out[(8 - 4) * SBLIMIT] = MULH3(t1, win[     8 - 4], 1) + buf[4*(8 - 4)];
+    buf[4 * ( 9 + 4     )] = MULH3(t0, win[18 + 9 + 4], 1);
+    buf[4 * ( 8 - 4     )] = MULH3(t0, win[18 + 8 - 4], 1);
+}
+
+void RENAME(ff_imdct36_blocks)(INTFLOAT *out, INTFLOAT *buf, INTFLOAT *in,
+                               int count, int switch_point, int block_type)
+{
+    int j;
+    for (j=0 ; j < count; j++) {
+        /* apply window & overlap with previous buffer */
+
+        /* select window */
+        int win_idx = (switch_point && j < 2) ? 0 : block_type;
+        INTFLOAT *win = RENAME(ff_mdct_win)[win_idx + (4 & -(j & 1))];
+
+        imdct36(out, buf, in, win);
+
+        in  += 18;
+        buf += ((j&3) != 3 ? 1 : (72-3));
+        out++;
+    }
+}