X-Git-Url: http://git.tuebingen.mpg.de/?p=paraslash.git;a=blobdiff_plain;f=bitstream.c;h=1139edc0d01dfe3668906f747809e0bfb055c18e;hp=2522b6d4e0a2be6e738fe5f1632c9f788e98a978;hb=748d1368bc96dd7e1af879df1ea41b4d52842f7e;hpb=ee3c423f1c081600367fd0da2b09e5a05e2088b7

diff --git a/bitstream.c b/bitstream.c
index 2522b6d4..1139edc0 100644
--- a/bitstream.c
+++ b/bitstream.c
@@ -27,9 +27,9 @@
 #include "wma.h"
 #include "bitstream.h"
 
-#define GET_DATA(v, table, i, wrap, size) \
+#define GET_DATA(v, table, i, size) \
 {\
-	const uint8_t *ptr = (const uint8_t *)table + i * wrap; \
+	const uint8_t *ptr = (const uint8_t *)table + i * size; \
 	switch (size) { \
 	case 1: \
 		v = *(const uint8_t *)ptr; \
@@ -54,10 +54,10 @@ static void alloc_table(struct vlc *vlc, int size)
 }
 
 static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
-		const void *bits, const void *codes, int codes_wrap,
-		int codes_size, uint32_t code_prefix, int n_prefix)
+		const void *bits, const void *codes, int codes_size,
+		uint32_t code_prefix, int n_prefix)
 {
-	int ret, i, j, k, n, table_size, table_index, nb, n1, idx, code_prefix2,
+	int i, j, k, n, table_size, table_index, nb, n1, idx, code_prefix2,
 		symbol;
 	uint32_t code;
 	VLC_TYPE(*table)[2];
@@ -72,10 +72,10 @@ static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
 		table[i][0] = -1;	//codes
 	}
 
-	/* first pass: map codes and compute auxillary table sizes */
+	/* map codes and compute auxillary table sizes */
 	for (i = 0; i < nb_codes; i++) {
-		GET_DATA(n, bits, i, 1, 1);
-		GET_DATA(code, codes, i, codes_wrap, codes_size);
+		GET_DATA(n, bits, i, 1);
+		GET_DATA(code, codes, i, codes_size);
 		/* we accept tables with holes */
 		if (n <= 0)
 			continue;
@@ -83,31 +83,33 @@ static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
 		/* if code matches the prefix, it is in the table */
 		n -= n_prefix;
 		code_prefix2 = code >> n;
-		if (n > 0 && code_prefix2 == code_prefix) {
-			if (n <= table_nb_bits) {
-				/* no need to add another table */
-				j = (code << (table_nb_bits - n)) & (table_size - 1);
-				nb = 1 << (table_nb_bits - n);
-				for (k = 0; k < nb; k++) {
-					if (table[j][1] /* bits */ != 0)
-						return -E_BAD_CODES;
-					table[j][1] = n;	//bits
-					table[j][0] = symbol;
-					j++;
+		if (n <= 0 || code_prefix2 != code_prefix)
+			continue;
+		if (n <= table_nb_bits) {
+			/* no need to add another table */
+			j = (code << (table_nb_bits - n)) & (table_size - 1);
+			nb = 1 << (table_nb_bits - n);
+			for (k = 0; k < nb; k++) {
+				if (table[j][1] /* bits */ != 0) {
+					PARA_EMERG_LOG("incorrect code\n");
+					exit(EXIT_FAILURE);
 				}
-			} else {
-				n -= table_nb_bits;
-				j = (code >> n) & ((1 << table_nb_bits) - 1);
-				/* compute table size */
-				n1 = -table[j][1];	//bits
-				if (n > n1)
-					n1 = n;
-				table[j][1] = -n1;	//bits
+				table[j][1] = n;	//bits
+				table[j][0] = symbol;
+				j++;
 			}
+		} else {
+			n -= table_nb_bits;
+			j = (code >> n) & ((1 << table_nb_bits) - 1);
+			/* compute table size */
+			n1 = -table[j][1];	//bits
+			if (n > n1)
+				n1 = n;
+			table[j][1] = -n1;	//bits
 		}
 	}
 
-	/* second pass : fill auxillary tables recursively */
+	/* fill auxillary tables recursively */
 	for (i = 0; i < table_size; i++) {
 		n = table[i][1];	//bits
 		if (n < 0) {
@@ -116,14 +118,10 @@ static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
 				n = table_nb_bits;
 				table[i][1] = -n;	//bits
 			}
-			ret = build_table(vlc, n, nb_codes,
-				bits, codes, codes_wrap, codes_size,
-				(code_prefix << table_nb_bits) | i,
+			idx = build_table(vlc, n, nb_codes, bits, codes,
+				codes_size, (code_prefix << table_nb_bits) | i,
 				n_prefix + table_nb_bits);
-			if (ret < 0)
-				return ret;
-			idx = ret;
-			/* note: realloc has been done, so reload tables */
+			/* vlc->table might have changed */
 			table = &vlc->table[table_index];
 			table[i][0] = idx;	//code
 		}
@@ -134,47 +132,76 @@ static int build_table(struct vlc *vlc, int table_nb_bits, int nb_codes,
 /**
  * Build VLC decoding tables suitable for use with get_vlc().
  *
- * \param nb_bits Set the decoding table size (2^nb_bits)
- * entries. The bigger it is, the faster is the decoding. But
- * it should not be too big to save memory and L1 cache. '9'
- * is a good compromise.
+ * \param vlc The structure to be initialized.
  *
- * \param nb_codes Number of vlcs codes.
+ * \param nb_bits Set the decoding table size (2^nb_bits) entries. The bigger
+ * it is, the faster is the decoding. But it should not be too big to save
+ * memory and L1 cache. '9' is a good compromise.
  *
- * \param bits Table which gives the size (in bits) of each
- * vlc code.
+ * \param nb_codes Number of vlcs codes.
  *
- * \param codes Table which gives the bit pattern of of each
- * vlc code.
+ * \param bits Table which gives the size (in bits) of each vlc code.
  *
- * \param codes_wrap The number of bytes between each entry of the
- * 'codes' tables.
+ * \param codes Table which gives the bit pattern of of each vlc code.
  *
- * \param codes_size The number of bytes of each entry of the
- * 'codes' tables.
+ * \param codes_size The number of bytes of each entry of the \a codes tables.
  *
  * The wrap and size parameters allow to use any memory configuration and
  * types (byte/word/long) to store the bits and codes tables.
  */
-int init_vlc(struct vlc *vlc, int nb_bits, int nb_codes,
-		const void *bits, const void *codes, int codes_wrap,
-		int codes_size)
+void init_vlc(struct vlc *vlc, int nb_bits, int nb_codes, const void *bits,
+		const void *codes, int codes_size)
 {
-	int ret;
-
-	PARA_INFO_LOG("nb_codes=%d\n", nb_codes);
+	PARA_INFO_LOG("nb_codes: %d\n", nb_codes);
 	vlc->bits = nb_bits;
 	vlc->table = NULL;
 	vlc->table_allocated = 0;
 	vlc->table_size = 0;
-	ret = build_table(vlc, nb_bits, nb_codes, bits,
-		codes, codes_wrap, codes_size, 0, 0);
-	if (ret < 0)
-		freep(&vlc->table);
-	return ret;
+	build_table(vlc, nb_bits, nb_codes, bits, codes, codes_size, 0, 0);
 }
 
 void free_vlc(struct vlc *vlc)
 {
 	freep(&vlc->table);
 }
+
+/**
+ * Parse a vlc code.
+ *
+ * \param gbc The getbit context structure.
+ *
+ * \param table The vlc tables to use.
+ *
+ * \param bits The number of bits which will be read at once, must be
+ * identical to nb_bits in init_vlc().
+ *
+ * \param max_depth The number of times bits bits must be read to completely
+ * read the longest vlc code = (max_vlc_length + bits - 1) / bits.
+ *
+ * \return The vlc code.
+ */
+int get_vlc(struct getbit_context *gbc, VLC_TYPE(*table)[2], int bits,
+		int max_depth)
+{
+	int n, idx, nb_bits, code;
+
+	idx = show_bits(gbc, bits);
+	code = table[idx][0];
+	n = table[idx][1];
+	if (max_depth > 1 && n < 0) {
+		skip_bits(gbc, bits);
+		nb_bits = -n;
+		idx = show_bits(gbc, nb_bits) + code;
+		code = table[idx][0];
+		n = table[idx][1];
+		if (max_depth > 2 && n < 0) {
+			skip_bits(gbc, nb_bits);
+			nb_bits = -n;
+			idx = show_bits(gbc, nb_bits) + code;
+			code = table[idx][0];
+			n = table[idx][1];
+		}
+	}
+	skip_bits(gbc, n);
+	return code >= 0? code : -E_VLC;
+}