From ef85c9a7bca5aa5b719a00070bd911ce23fb2dcf Mon Sep 17 00:00:00 2001
From: Hajime Hoshi <hajimehoshi@gmail.com>
Date: Thu, 15 Jun 2017 03:20:00 +0900
Subject: [PATCH] audio/mp3: Move L3_Antialias to Go

---
 audio/mp3/l3.go   | 33 +++++++++++++++++++++++++++++++++
 audio/mp3/pdmp3.c | 36 ------------------------------------
 audio/mp3/pdmp3.h |  1 +
 3 files changed, 34 insertions(+), 36 deletions(-)

diff --git a/audio/mp3/l3.go b/audio/mp3/l3.go
index 7306881eb..b5c0f6a8f 100644
--- a/audio/mp3/l3.go
+++ b/audio/mp3/l3.go
@@ -174,6 +174,39 @@ func L3_Stereo(gr C.unsigned) {
 	}
 }
 
+var (
+	cs = [8]float32{0.857493, 0.881742, 0.949629, 0.983315, 0.995518, 0.999161, 0.999899, 0.999993}
+	ca = [8]float32{-0.514496, -0.471732, -0.313377, -0.181913, -0.094574, -0.040966, -0.014199, -0.003700}
+)
+
+//export L3_Antialias
+func L3_Antialias(gr C.unsigned, ch C.unsigned) {
+	/* No antialiasing is done for short blocks */
+	if (C.g_side_info.win_switch_flag[gr][ch] == 1) &&
+		(C.g_side_info.block_type[gr][ch] == 2) &&
+		(C.g_side_info.mixed_block_flag[gr][ch]) == 0 {
+		return
+	}
+	/* Setup the limit for how many subbands to transform */
+	sblim := 32
+	if (C.g_side_info.win_switch_flag[gr][ch] == 1) &&
+		(C.g_side_info.block_type[gr][ch] == 2) &&
+		(C.g_side_info.mixed_block_flag[gr][ch] == 1) {
+		sblim = 2
+	}
+	/* Do the actual antialiasing */
+	for sb := 1; sb < sblim; sb++ {
+		for i := 0; i < 8; i++ {
+			li := 18*sb - 1 - i
+			ui := 18*sb + i
+			lb := C.g_main_data.is[gr][ch][li]*C.float(cs[i]) - C.g_main_data.is[gr][ch][ui]*C.float(ca[i])
+			ub := C.g_main_data.is[gr][ch][ui]*C.float(cs[i]) + C.g_main_data.is[gr][ch][li]*C.float(ca[i])
+			C.g_main_data.is[gr][ch][li] = lb
+			C.g_main_data.is[gr][ch][ui] = ub
+		}
+	}
+}
+
 var store = [2][32][18]float32{}
 
 //export L3_Hybrid_Synthesis
diff --git a/audio/mp3/pdmp3.c b/audio/mp3/pdmp3.c
index fb60d7036..630c210e2 100644
--- a/audio/mp3/pdmp3.c
+++ b/audio/mp3/pdmp3.c
@@ -44,7 +44,6 @@ static void audio_write(unsigned *samples,unsigned nsamples,int sample_rate);
 static void audio_write_raw(unsigned *samples,unsigned nsamples);
 static void Decode_L3_Init_Song(void);
 static void Error(const char *s,int e);
-static void L3_Antialias(unsigned gr,unsigned ch);
 static void L3_Requantize(unsigned gr,unsigned ch);
 static void L3_Reorder(unsigned gr,unsigned ch);
 static void Read_Ancillary(void);
@@ -65,9 +64,6 @@ static const unsigned g_mpeg1_bitrates[3 /* layer 1-3 */][15 /* header bitrate_i
 },
 g_sampling_frequency[3] = { 44100 * Hz,48000 * Hz,32000 * Hz };
 
-static const float //ci[8]={-0.6,-0.535,-0.33,-0.185,-0.095,-0.041,-0.0142,-0.0037},
-  cs[8]={0.857493,0.881742,0.949629,0.983315,0.995518,0.999161,0.999899,0.999993},
-  ca[8]={-0.514496,-0.471732,-0.313377,-0.181913,-0.094574,-0.040966,-0.014199,-0.003700};
 #ifdef POW34_ITERATE
 static const float powtab34[32] = {
   0.000000f,1.000000f,2.519842f,4.326749f,6.349605f,8.549880f,10.902724f,
@@ -422,38 +418,6 @@ static void Decode_L3_Init_Song(void){
   synth_init = 1;
 }
 
-/**Description: TBD
-* Parameters: TBD
-* Return value: TBD
-* Author: Krister Lagerström(krister@kmlager.com) **/
-static void L3_Antialias(unsigned gr,unsigned ch){
-  unsigned sb /* subband of 18 samples */,i,sblim,ui,li;
-  float ub,lb;
-
-  /* No antialiasing is done for short blocks */
-  if((g_side_info.win_switch_flag[gr][ch] == 1) &&
-     (g_side_info.block_type[gr][ch] == 2) &&
-     (g_side_info.mixed_block_flag[gr][ch]) == 0) {
-    return; /* Done */
-  }
-  /* Setup the limit for how many subbands to transform */
-  sblim =((g_side_info.win_switch_flag[gr][ch] == 1) &&
-    (g_side_info.block_type[gr][ch] == 2) &&
-    (g_side_info.mixed_block_flag[gr][ch] == 1))?2:32;
-  /* Do the actual antialiasing */
-  for(sb = 1; sb < sblim; sb++) {
-    for(i = 0; i < 8; i++) {
-      li = 18*sb-1-i;
-      ui = 18*sb+i;
-      lb = g_main_data.is[gr][ch][li]*cs[i] - g_main_data.is[gr][ch][ui]*ca[i];
-      ub = g_main_data.is[gr][ch][ui]*cs[i] + g_main_data.is[gr][ch][li]*ca[i];
-      g_main_data.is[gr][ch][li] = lb;
-      g_main_data.is[gr][ch][ui] = ub;
-    }
-  }
-  return; /* Done */
-}
-
 /**Description: TBD
 * Parameters: TBD
 * Return value: TBD
diff --git a/audio/mp3/pdmp3.h b/audio/mp3/pdmp3.h
index f6ac84a7c..ed0d5d047 100644
--- a/audio/mp3/pdmp3.h
+++ b/audio/mp3/pdmp3.h
@@ -100,6 +100,7 @@ static int Read_Header(void);
 void Read_Huffman(unsigned part_2_start,unsigned gr,unsigned ch);
 
 void L3_Stereo(unsigned gr);
+void L3_Antialias(unsigned gr,unsigned ch);
 void L3_Hybrid_Synthesis(unsigned gr,unsigned ch);
 void L3_Frequency_Inversion(unsigned gr,unsigned ch);
 void L3_Subband_Synthesis(unsigned gr,unsigned ch, unsigned* outdata);