audio/mp3: Move Read_Huffman to Go

audio/mp3/huffman.go

@@ -348,27 +348,22 @@ var huffmanMain = [...]huffTables{
 	{huffmanTable[2261:], 31, 0},   /* Table 33 */
 }
 
-//export Huffman_Decode
+func huffmanDecode(table_num int) (x, y, v, w int, err error) {
-func Huffman_Decode(table_num C.unsigned, x, y, v, w *C.int32_t) C.int {
 	point := 0
 	error := 1
 	bitsleft := 32
 	treelen := huffmanMain[table_num].treelen
 	linbits := huffmanMain[table_num].linbits
 	if treelen == 0 { /* Check for empty tables */
-		*x = 0
+		return 0, 0, 0, 0, nil
-		*y = 0
-		*v = 0
-		*w = 0
-		return C.OK
 	}
 	htptr := huffmanMain[table_num].hufftable
 	for { /* Start reading the Huffman code word,bit by bit */
 		/* Check if we've matched a code word */
 		if (htptr[point] & 0xff00) == 0 {
 			error = 0
-			*x = C.int32_t((htptr[point] >> 4) & 0xf)
+			x = int((htptr[point] >> 4) & 0xf)
-			*y = C.int32_t(htptr[point] & 0xf)
+			y = int(htptr[point] & 0xf)
 			break
 		}
 		if getMainBit() != 0 { /* Go right in tree */
@@ -390,43 +385,38 @@ func Huffman_Decode(table_num C.unsigned, x, y, v, w *C.int32_t) C.int {
 	if error != 0 { /* Check for error. */
 		err := fmt.Errorf("mp3: illegal Huff code in data. bleft = %d, point = %d. tab = %d.",
 			bitsleft, point, table_num)
-		*x = 0
+		return 0, 0, 0, 0, err
-		*y = 0
-		g_error = err
 	}
 	if table_num > 31 { /* Process sign encodings for quadruples tables. */
-		*v = (*y >> 3) & 1
+		v = (y >> 3) & 1
-		*w = (*y >> 2) & 1
+		w = (y >> 2) & 1
-		*x = (*y >> 1) & 1
+		x = (y >> 1) & 1
-		*y = *y & 1
+		y = y & 1
-		if (*v > 0) && (getMainBit() == 1) {
+		if (v > 0) && (getMainBit() == 1) {
-			*v = -*v
+			v = -v
 		}
-		if (*w > 0) && (getMainBit() == 1) {
+		if (w > 0) && (getMainBit() == 1) {
-			*w = -*w
+			w = -w
 		}
-		if (*x > 0) && (getMainBit() == 1) {
+		if (x > 0) && (getMainBit() == 1) {
-			*x = -*x
+			x = -x
 		}
-		if (*y > 0) && (getMainBit() == 1) {
+		if (y > 0) && (getMainBit() == 1) {
-			*y = -*y
+			y = -y
 		}
 	} else {
-		if (linbits > 0) && (*x == 15) {
+		if (linbits > 0) && (x == 15) {
-			*x += C.int32_t(getMainBits(linbits)) /* Get linbits */
+			x += getMainBits(linbits) /* Get linbits */
 		}
-		if (*x > 0) && (getMainBit() == 1) {
+		if (x > 0) && (getMainBit() == 1) {
-			*x = -*x /* Get sign bit */
+			x = -x /* Get sign bit */
 		}
-		if (linbits > 0) && (*y == 15) {
+		if (linbits > 0) && (y == 15) {
-			*y += C.int32_t(getMainBits(linbits)) /* Get linbits */
+			y += getMainBits(linbits) /* Get linbits */
 		}
-		if (*y > 0) && (getMainBit() == 1) {
+		if (y > 0) && (getMainBit() == 1) {
-			*y = -*y /* Get sign bit */
+			y = -y /* Get sign bit */
 		}
 	}
-	if error != 0 {
+	return x, y, v, w, nil
-		return C.ERROR
-	}
-	return C.OK
 }

audio/mp3/maindata.go

@@ -71,7 +71,7 @@ func Read_Main_L3() C.int {
 	}
 	for gr := 0; gr < 2; gr++ {
 		for ch := 0; ch < nch; ch++ {
-			part_2_start := Get_Main_Pos()
+			part_2_start := int(Get_Main_Pos())
 			/* Number of bits in the bitstream for the bands */
 			slen1 := mpeg1_scalefac_sizes[C.g_side_info.scalefac_compress[gr][ch]][0]
 			slen2 := mpeg1_scalefac_sizes[C.g_side_info.scalefac_compress[gr][ch]][1]
@@ -149,7 +149,10 @@ func Read_Main_L3() C.int {
 				}
 			}
 			/* Read Huffman coded data. Skip stuffing bits. */
-			C.Read_Huffman(part_2_start, C.uint(gr), C.uint(ch))
+			if err := readHuffman(part_2_start, gr, ch); err != nil {
+				g_error = err
+				return C.ERROR
+			}
 		}
 	}
 	/* The ancillary data is stored here,but we ignore it. */

audio/mp3/pdmp3.c

@@ -350,76 +350,6 @@ static void Decode_L3_Init_Song(void){
   synth_init = 1;
 }
 
-/**Description: called by Read_Main_L3 to read Huffman coded data from bitstream.
-* Parameters: None
-* Return value: None. The data is stored in g_main_data.is[ch][gr][freqline].
-* Author: Krister Lagerström(krister@kmlager.com) **/
-void Read_Huffman(unsigned part_2_start,unsigned gr,unsigned ch){
-  int32_t x,y,v,w;
-  unsigned table_num,is_pos,bit_pos_end,sfreq;
-  unsigned region_1_start,region_2_start; /* region_0_start = 0 */
-
-  /* Check that there is any data to decode. If not,zero the array. */
-  if(g_side_info.part2_3_length[gr][ch] == 0) {
-    for(is_pos = 0; is_pos < 576; is_pos++)
-      g_main_data.is[gr][ch][is_pos] = 0.0;
-    return;
-  }
-  /* Calculate bit_pos_end which is the index of the last bit for this part. */
-  bit_pos_end = part_2_start + g_side_info.part2_3_length[gr][ch] - 1;
-  /* Determine region boundaries */
-  if((g_side_info.win_switch_flag[gr][ch] == 1)&&
-     (g_side_info.block_type[gr][ch] == 2)) {
-    region_1_start = 36;  /* sfb[9/3]*3=36 */
-    region_2_start = 576; /* No Region2 for short block case. */
-  }else{
-    sfreq = g_frame_header.sampling_frequency;
-    region_1_start =
-      g_sf_band_indices[sfreq].l[g_side_info.region0_count[gr][ch] + 1];
-    region_2_start =
-      g_sf_band_indices[sfreq].l[g_side_info.region0_count[gr][ch] +
-        g_side_info.region1_count[gr][ch] + 2];
-  }
-  /* Read big_values using tables according to region_x_start */
-  for(is_pos = 0; is_pos < g_side_info.big_values[gr][ch] * 2; is_pos++) {
-    if(is_pos < region_1_start) {
-      table_num = g_side_info.table_select[gr][ch][0];
-    } else if(is_pos < region_2_start) {
-      table_num = g_side_info.table_select[gr][ch][1];
-    }else table_num = g_side_info.table_select[gr][ch][2];
-    /* Get next Huffman coded words */
-   (void) Huffman_Decode(table_num,&x,&y,&v,&w);
-    /* In the big_values area there are two freq lines per Huffman word */
-    g_main_data.is[gr][ch][is_pos++] = x;
-    g_main_data.is[gr][ch][is_pos] = y;
-  }
-  /* Read small values until is_pos = 576 or we run out of huffman data */
-  table_num = g_side_info.count1table_select[gr][ch] + 32;
-  for(is_pos = g_side_info.big_values[gr][ch] * 2;
-      (is_pos <= 572) &&(Get_Main_Pos() <= bit_pos_end); is_pos++) {
-    /* Get next Huffman coded words */
-   (void) Huffman_Decode(table_num,&x,&y,&v,&w);
-    g_main_data.is[gr][ch][is_pos++] = v;
-    if(is_pos >= 576) break;
-    g_main_data.is[gr][ch][is_pos++] = w;
-    if(is_pos >= 576) break;
-    g_main_data.is[gr][ch][is_pos++] = x;
-    if(is_pos >= 576) break;
-    g_main_data.is[gr][ch][is_pos] = y;
-  }
-  /* Check that we didn't read past the end of this section */
-  if(Get_Main_Pos() >(bit_pos_end+1)) /* Remove last words read */
-    is_pos -= 4;
-  /* Setup count1 which is the index of the first sample in the rzero reg. */
-  g_side_info.count1[gr][ch] = is_pos;
-  /* Zero out the last part if necessary */
-  for(/* is_pos comes from last for-loop */; is_pos < 576; is_pos++)
-    g_main_data.is[gr][ch][is_pos] = 0.0;
-  /* Set the bitpos to point to the next part to read */
- (void) Set_Main_Pos(bit_pos_end+1);
-  return;  /* Done */
-}
-
 /**Description: output audio data
 * Parameters: Pointers to the samples,the number of samples
 * Return value: None

audio/mp3/pdmp3.h

@@ -97,7 +97,6 @@ int Set_Main_Pos(unsigned bit_pos);
 int Read_Main_L3(void);
 int Read_Audio_L3(void);
 static int Read_Header(void);
-void Read_Huffman(unsigned part_2_start,unsigned gr,unsigned ch);
 
 void L3_Requantize(unsigned gr,unsigned ch);
 void L3_Reorder(unsigned gr,unsigned ch);
@@ -109,6 +108,4 @@ void L3_Subband_Synthesis(unsigned gr,unsigned ch, unsigned* outdata);
 
 int Read_CRC(void);
 
-int Huffman_Decode(unsigned table_num, int32_t* x, int32_t*y, int32_t* v, int32_t* w);
-
 #endif

audio/mp3/read.go

@@ -0,0 +1,110 @@
+// Copyright 2017 The Ebiten Authors
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// +build !js
+
+package mp3
+
+// #include "pdmp3.h"
+//
+// extern t_mpeg1_main_data g_main_data;
+// extern t_mpeg1_side_info g_side_info;
+// extern t_mpeg1_header    g_frame_header;
+import "C"
+
+func readHuffman(part_2_start, gr, ch int) error {
+	/* Check that there is any data to decode. If not,zero the array. */
+	if C.g_side_info.part2_3_length[gr][ch] == 0 {
+		for is_pos := 0; is_pos < 576; is_pos++ {
+			C.g_main_data.is[gr][ch][is_pos] = 0.0
+		}
+		return nil
+	}
+	/* Calculate bit_pos_end which is the index of the last bit for this part. */
+	bit_pos_end := part_2_start + int(C.g_side_info.part2_3_length[gr][ch]) - 1
+	/* Determine region boundaries */
+	region_1_start := 0
+	region_2_start := 0
+	if (C.g_side_info.win_switch_flag[gr][ch] == 1) && (C.g_side_info.block_type[gr][ch] == 2) {
+		region_1_start = 36  /* sfb[9/3]*3=36 */
+		region_2_start = 576 /* No Region2 for short block case. */
+	} else {
+		sfreq := C.g_frame_header.sampling_frequency
+		region_1_start =
+			sfBandIndicesSet[sfreq].l[C.g_side_info.region0_count[gr][ch]+1]
+		region_2_start =
+			sfBandIndicesSet[sfreq].l[C.g_side_info.region0_count[gr][ch]+
+				C.g_side_info.region1_count[gr][ch]+2]
+	}
+	/* Read big_values using tables according to region_x_start */
+	for is_pos := 0; is_pos < int(C.g_side_info.big_values[gr][ch])*2; is_pos++ {
+		table_num := 0
+		if is_pos < region_1_start {
+			table_num = int(C.g_side_info.table_select[gr][ch][0])
+		} else if is_pos < region_2_start {
+			table_num = int(C.g_side_info.table_select[gr][ch][1])
+		} else {
+			table_num = int(C.g_side_info.table_select[gr][ch][2])
+		}
+		/* Get next Huffman coded words */
+		x, y, _, _, err := huffmanDecode(table_num)
+		if err != nil {
+			return err
+		}
+		/* In the big_values area there are two freq lines per Huffman word */
+		C.g_main_data.is[gr][ch][is_pos] = C.float(x)
+		is_pos++
+		C.g_main_data.is[gr][ch][is_pos] = C.float(y)
+	}
+	/* Read small values until is_pos = 576 or we run out of huffman data */
+	table_num := int(C.g_side_info.count1table_select[gr][ch]) + 32
+	is_pos := int(C.g_side_info.big_values[gr][ch]) * 2
+	for ; (is_pos <= 572) && (int(Get_Main_Pos()) <= bit_pos_end); is_pos++ {
+		/* Get next Huffman coded words */
+		x, y, v, w, err := huffmanDecode(table_num)
+		if err != nil {
+			return err
+		}
+		C.g_main_data.is[gr][ch][is_pos] = C.float(v)
+		is_pos++
+		if is_pos >= 576 {
+			break
+		}
+		C.g_main_data.is[gr][ch][is_pos] = C.float(w)
+		is_pos++
+		if is_pos >= 576 {
+			break
+		}
+		C.g_main_data.is[gr][ch][is_pos] = C.float(x)
+		is_pos++
+		if is_pos >= 576 {
+			break
+		}
+		C.g_main_data.is[gr][ch][is_pos] = C.float(y)
+	}
+	/* Check that we didn't read past the end of this section */
+	if int(C.Get_Main_Pos()) > (bit_pos_end + 1) {
+		/* Remove last words read */
+		is_pos -= 4
+	}
+	/* Setup count1 which is the index of the first sample in the rzero reg. */
+	C.g_side_info.count1[gr][ch] = C.unsigned(is_pos)
+	/* Zero out the last part if necessary */
+	for ; /* is_pos comes from last for-loop */ is_pos < 576; is_pos++ {
+		C.g_main_data.is[gr][ch][is_pos] = 0.0
+	}
+	/* Set the bitpos to point to the next part to read */
+	C.Set_Main_Pos(C.unsigned(bit_pos_end) + 1)
+	return nil
+}