From: Andre Noll <maan@systemlinux.org>
Date: Tue, 13 Mar 2007 22:15:57 +0000 (+0100)
Subject: mp3_afh.c: Switch to memory mapped input file
X-Git-Tag: v0.2.16~22
X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=commitdiff_plain;h=381d053808a93efec734496bfd09f40176d4e6ac

mp3_afh.c: Switch to memory mapped input file
---

diff --git a/mp3_afh.c b/mp3_afh.c
index d26d9094..a3e3c5c3 100644
--- a/mp3_afh.c
+++ b/mp3_afh.c
@@ -197,38 +197,37 @@ static int compare_headers(struct mp3header *h1,struct mp3header *h2)
  * zero means that we did not retrieve a valid frame header, and a negative
  * return value indicates an error.
  */
-static int get_header(FILE *file, struct mp3header *header)
+static int get_header(unsigned char *map, off_t numbytes, off_t *fpos,
+	struct mp3header *header)
 {
-	unsigned char buffer[FRAME_HEADER_SIZE];
 	int fl, ret;
 
-	if (!file || !header)
-		return -E_MP3_NO_FILE;
-	ret = para_fread(buffer, FRAME_HEADER_SIZE, 1, file);
-	if (ret < FRAME_HEADER_SIZE) {
+	if (*fpos + FRAME_HEADER_SIZE > numbytes) {
+		*fpos = numbytes - 1;
 		header->sync = 0;
-		return ret < 0? ret : 0;
+		return 0;
 	}
-	header->layer = (buffer[1] >> 1) & 3;
-	header->sync = (((int)buffer[0]<<4) | ((int)(buffer[1]&0xE0)>>4));
-	if (buffer[1] & 0x10)
-		header->version = (buffer[1] >> 3) & 1;
+	header->layer = (map[*fpos + 1] >> 1) & 3;
+	header->sync = (((int)map[*fpos]<<4) | ((int)(map[*fpos + 1]&0xE0)>>4));
+	if (map[*fpos + 1] & 0x10)
+		header->version = (map[*fpos + 1] >> 3) & 1;
 	else
 		header->version = 2;
 	if ((header->sync != 0xFFE) || (header->layer != 1)) {
+		ret = 0;
 		header->sync = 0;
-//		PARA_DEBUG_LOG("%s: header not found\n", __func__);
-		return 0;
+		goto out;
 	}
-	header->crc = buffer[1] & 1;
-	header->bitrate = (buffer[2] >> 4) & 0x0F;
-//	PARA_DEBUG_LOG("%s: found header, bitrate: %u\n", __func__,
-//		header->bitrate);
-	header->freq = (buffer[2] >> 2) & 0x3;
-	header->padding = (buffer[2] >>1) & 0x1;
-	header->mode = (buffer[3] >> 6) & 0x3;
+	header->crc = map[*fpos + 1] & 1;
+	header->bitrate = (map[*fpos + 2] >> 4) & 0x0F;
+	header->freq = (map[*fpos + 2] >> 2) & 0x3;
+	header->padding = (map[*fpos + 2] >>1) & 0x1;
+	header->mode = (map[*fpos + 3] >> 6) & 0x3;
 	fl = frame_length(header);
-	return (fl >= MIN_FRAME_SIZE)? fl : -E_FRAME_LENGTH;
+	ret = (fl >= MIN_FRAME_SIZE)? fl : -E_FRAME_LENGTH;
+out:
+	*fpos += FRAME_HEADER_SIZE;
+	return ret;
 }
 
 /**
@@ -239,82 +238,66 @@ static int get_header(FILE *file, struct mp3header *header)
  * returned.
  *
  */
-static int mp3_seek_next_header(FILE *file)
+static int mp3_seek_next_header(unsigned char *map, off_t numbytes, off_t *fpos)
 {
-	int k, l = 0, c, first_len, ret;
+	int k, l = 0, first_len;
 	struct mp3header h, h2;
 	long valid_start = 0;
 
 	while (1) {
-		while ((c = fgetc(file)) != 255 && (c != EOF))
-			; /* nothing */
-		if (c != 255)
+		while ((*fpos)++ < numbytes && map[*fpos] != 0xff)
+			;
+		if (*fpos >= numbytes)
 			return 0;
-		ungetc(c, file);
-		valid_start = ftell(file);
-		first_len = get_header(file, &h);
+		valid_start = *fpos;
+		first_len = get_header(map, numbytes, fpos, &h);
 		if (first_len <= 0)
 			continue;
-		ret = para_fseek(file, first_len - FRAME_HEADER_SIZE, SEEK_CUR);
-		if (ret < 0)
-			return ret;
+		*fpos += first_len - FRAME_HEADER_SIZE;
 		for (k = 1; k < MIN_CONSEC_GOOD_FRAMES; k++) {
-			if ((l = get_header(file, &h2)) <= 0)
+			if ((l = get_header(map, numbytes, fpos, &h2)) <= 0)
 				break;
 			if (!compare_headers(&h, &h2))
 				break;
-			ret = para_fseek(file, l - FRAME_HEADER_SIZE, SEEK_CUR);
-			if (ret < 0)
-				return ret;
+			*fpos += l - FRAME_HEADER_SIZE;
 		}
 		if (k == MIN_CONSEC_GOOD_FRAMES) {
-			ret = para_fseek(file, valid_start, SEEK_SET);
-			if (ret < 0)
-				return ret;
+			*fpos = valid_start;
 			memcpy(&(mp3.header), &h2, sizeof(struct mp3header));
 			return first_len;
 		}
 	}
 }
 
-static int mp3_get_id3(FILE *file)
+static void mp3_get_id3(unsigned char *map, off_t numbytes, off_t *fpos)
 {
-	char fbuf[4];
-	int ret;
-
 	mp3.id3_isvalid = 0;
 	mp3.id3.title[0] = '\0';
 	mp3.id3.artist[0] = '\0';
 	mp3.id3.album[0] = '\0';
 	mp3.id3.comment[0] = '\0';
 	mp3.id3.year[0] = '\0';
-	ret = para_fseek(file, -128, SEEK_END);
-	if (ret < 0 )
-		return ret;
-	if (para_fread(fbuf, 1, 3, file) < 0)
-		return -E_FREAD;
-	fbuf[3] = '\0';
-	if (strcmp("TAG", fbuf)) {
+	if (numbytes < 128)
+		return;
+	*fpos = numbytes - 128;
+	if (strncmp("TAG", map + *fpos, 3)) {
 		PARA_INFO_LOG("%s", "no id3 tag\n");
-		return 0;
+		return;
 	}
-	ret = para_fseek(file, -125, SEEK_END);
-	if (ret < 0)
-		return ret;
-	if (para_fread(mp3.id3.title, 1, 30, file) != 30)
-		return -E_FREAD;
+	*fpos = numbytes - 125;
+	memcpy(mp3.id3.title, map + *fpos, 30);
+	*fpos += 30;
 	mp3.id3.title[30] = '\0';
-	if (para_fread(mp3.id3.artist, 1, 30, file) != 30)
-		return -E_FREAD;
+	memcpy(mp3.id3.artist, map + *fpos, 30);
+	*fpos += 30;
 	mp3.id3.artist[30] = '\0';
-	if (para_fread(mp3.id3.album, 1, 30, file) != 30)
-		return -E_FREAD;
+	memcpy(mp3.id3.album, map + *fpos, 30);
+	*fpos += 30;
 	mp3.id3.album[30] = '\0';
-	if (para_fread(mp3.id3.year, 1, 4, file) != 4)
-		return -E_FREAD;
+	memcpy(mp3.id3.year, map + *fpos, 4);
+	*fpos += 4;
 	mp3.id3.year[4] = '\0';
-	if (para_fread(mp3.id3.comment, 1, 30, file) != 30)
-		return -E_FREAD;
+	memcpy(mp3.id3.comment, map + *fpos, 30);
 	mp3.id3.comment[30] = '\0';
 	mp3.id3_isvalid = 1;
 	unpad(mp3.id3.title);
@@ -322,54 +305,46 @@ static int mp3_get_id3(FILE *file)
 	unpad(mp3.id3.album);
 	unpad(mp3.id3.year);
 	unpad(mp3.id3.comment);
-	return 1;
 }
 
-static int find_valid_start(FILE *file)
+static int find_valid_start(unsigned char *map, off_t numbytes, off_t *fpos)
 {
-	int ret, frame_len;
+	int frame_len;
 
-	frame_len = get_header(file, &mp3.header);
+	frame_len = get_header(map, numbytes, fpos, &mp3.header);
 	if (frame_len < 0)
 		return frame_len;
 	if (!frame_len) {
-		frame_len = mp3_seek_next_header(file);
+		frame_len = mp3_seek_next_header(map, numbytes, fpos);
 		if (frame_len <= 0)
 			return frame_len;
-	} else {
-		ret = para_fseek(file, -FRAME_HEADER_SIZE, SEEK_CUR);
-		if (ret < 0)
-			return ret;
-	}
+	} else
+		*fpos -= FRAME_HEADER_SIZE;
 	if (frame_len <= 1)
 		return -E_FRAME_LENGTH;
 	return frame_len;
 }
 
-static int mp3_read_info(FILE *file, struct audio_format_info *afi)
+static int mp3_read_info(unsigned char *map, off_t numbytes,
+		struct audio_format_info *afi)
 {
 	long fl_avg = 0, freq_avg = 0, br_avg = 0;
 	int ret, len = 0, old_br = -1;
 	struct timeval total_time = {0, 0};
 	unsigned chunk_table_size = 1000; /* gets increased on demand */
+	off_t fpos = 0;
 
 	afi->chunks_total = 0;
 	afi->chunk_table = para_malloc(chunk_table_size * sizeof(size_t));
-	ret = mp3_get_id3(file);
-	if (ret < 0)
-		goto err_out;
-	rewind(file);
+	mp3_get_id3(map, numbytes, &fpos);
+	fpos = 0;
 	mp3.vbr = 0;
 	mp3.freq = 0;
 	while (1) {
 		int freq, br, fl;
 		struct timeval tmp, cct; /* current chunk time */
-		if (len > 0) {
-			ret = para_fseek(file, len, SEEK_CUR);
-			if (ret < 0)
-				goto err_out;
-		}
-		len = find_valid_start(file);
+		fpos += len;
+		len = find_valid_start(map, numbytes, &fpos);
 		if (len <= 0)
 			break;
 		freq = header_frequency(&mp3.header);
@@ -388,7 +363,7 @@ static int mp3_read_info(FILE *file, struct audio_format_info *afi)
 			afi->chunk_table = para_realloc(afi->chunk_table,
 				chunk_table_size * sizeof(size_t));
 		}
-		afi->chunk_table[afi->chunks_total] = ftell(file);
+		afi->chunk_table[afi->chunks_total] = fpos;
 //		if (afi->chunks_total < 10 || !(afi->chunks_total % 1000))
 //			PARA_INFO_LOG("chunk #%lu: %zd\n", afi->chunks_total,
 //				afi->chunk_table[afi->chunks_total]);
@@ -402,7 +377,7 @@ static int mp3_read_info(FILE *file, struct audio_format_info *afi)
 		}
 		freq_avg += (freq - freq_avg) / (afi->chunks_total + 1);
 		fl_avg += (fl - fl_avg) / (afi->chunks_total + 1);
-		br_avg += (br - br_avg) / (afi->chunks_total + 1);
+		br_avg += (br - br_avg) / ((long)afi->chunks_total + 1);
 		if (old_br != br)
 			mp3.vbr = 1;
 		old_br = br;
@@ -410,15 +385,11 @@ static int mp3_read_info(FILE *file, struct audio_format_info *afi)
 	ret = -E_MP3_INFO;
 	if (!afi->chunks_total || !freq_avg || !br_avg)
 		goto err_out;
-	ret= para_fseek(file, 0, SEEK_END);
-	if (ret < 0)
-		goto err_out;
-	afi->chunk_table[afi->chunks_total] = ftell(file);
+	afi->chunk_table[afi->chunks_total] = numbytes - 1;
 	mp3.br_average = br_avg;
 	mp3.freq = freq_avg;
 	afi->seconds_total = (tv2ms(&total_time) + 500) / 1000;
 	tv_divide(afi->chunks_total, &total_time, &afi->chunk_tv);
-	rewind(file);
 	PARA_DEBUG_LOG("%lu chunks, each %lums\n", afi->chunks_total,
 		tv2ms(&afi->chunk_tv));
 	tv_scale(3, &afi->chunk_tv, &afi->eof_tv);
@@ -438,7 +409,7 @@ static int mp3_get_file_info(FILE *file, char *map, off_t numbytes,
 {
 	int ret;
 
-	ret = mp3_read_info(file, afi);
+	ret = mp3_read_info((unsigned char *)map, numbytes, afi);
 	if (ret < 0)
 		return ret;
 	write_info_str(afi);