Update CRC16 for larger data blocks when decoding.

3 files changed, 75 insertions, 28 deletions

diff --git a/src/libFLAC/bitreader.c b/src/libFLAC/bitreader.c
index baafcf33..683e9f84 100644
--- a/src/libFLAC/bitreader.c
+++ b/src/libFLAC/bitreader.c
@@ -1,6 +1,6 @@
 /* libFLAC - Free Lossless Audio Codec library
  * Copyright (C) 2000-2009  Josh Coalson
- * Copyright (C) 2011-2016  Xiph.Org Foundation
+ * Copyright (C) 2011-2018  Xiph.Org Foundation
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -109,6 +109,7 @@ struct FLAC__BitReader {
 	uint32_t consumed_words; /* #words ... */
 	uint32_t consumed_bits; /* ... + (#bits of head word) already consumed from the front of buffer */
 	uint32_t read_crc16; /* the running frame CRC */
+	uint32_t crc16_offset; /* the number of words in the current buffer that should not be CRC'd */
 	uint32_t crc16_align; /* the number of bits in the current consumed word that should not be CRC'd */
 	FLAC__BitReaderReadCallback read_callback;
 	void *client_data;
@@ -117,32 +118,33 @@ struct FLAC__BitReader {
 static inline void crc16_update_word_(FLAC__BitReader *br, brword word)
 {
 	register uint32_t crc = br->read_crc16;
-#if FLAC__BYTES_PER_WORD == 4
-	switch(br->crc16_align) {
-		case  0: crc = FLAC__CRC16_UPDATE((uint32_t)(word >> 24), crc); /* Falls through. */
-		case  8: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 16) & 0xff), crc); /* Falls through. */
-		case 16: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 8) & 0xff), crc); /* Falls through. */
-		case 24: br->read_crc16 = FLAC__CRC16_UPDATE((uint32_t)(word & 0xff), crc); /* Falls through. */
-	}
-#elif FLAC__BYTES_PER_WORD == 8
-	switch(br->crc16_align) {
-		case  0: crc = FLAC__CRC16_UPDATE((uint32_t)(word >> 56), crc); /* Falls through. */
-		case  8: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 48) & 0xff), crc); /* Falls through. */
-		case 16: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 40) & 0xff), crc); /* Falls through. */
-		case 24: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 32) & 0xff), crc); /* Falls through. */
-		case 32: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 24) & 0xff), crc); /* Falls through. */
-		case 40: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 16) & 0xff), crc); /* Falls through. */
-		case 48: crc = FLAC__CRC16_UPDATE((uint32_t)((word >> 8) & 0xff), crc); /* Falls through. */
-		case 56: br->read_crc16 = FLAC__CRC16_UPDATE((uint32_t)(word & 0xff), crc);
-	}
-#else
+
 	for( ; br->crc16_align < FLAC__BITS_PER_WORD; br->crc16_align += 8)
 		crc = FLAC__CRC16_UPDATE((uint32_t)((word >> (FLAC__BITS_PER_WORD-8-br->crc16_align)) & 0xff), crc);
+
 	br->read_crc16 = crc;
-#endif
 	br->crc16_align = 0;
 }
 
+static inline void crc16_update_block_(FLAC__BitReader *br)
+{
+	if(br->crc16_align)
+		crc16_update_word_(br, br->buffer[br->crc16_offset++]);
+
+#if FLAC__BYTES_PER_WORD == 4
+	br->read_crc16 = FLAC__crc16_update_words32(br->buffer + br->crc16_offset, br->consumed_words - br->crc16_offset, br->read_crc16);
+#elif FLAC__BYTES_PER_WORD == 8
+	br->read_crc16 = FLAC__crc16_update_words64(br->buffer + br->crc16_offset, br->consumed_words - br->crc16_offset, br->read_crc16);
+#else
+	unsigned i;
+
+	for(i = br->crc16_offset; i < br->consumed_words; i++)
+		crc16_update_word_(br, br->buffer[i]);
+#endif
+
+	br->crc16_offset = 0;
+}
+
 static FLAC__bool bitreader_read_from_client_(FLAC__BitReader *br)
 {
 	uint32_t start, end;
@@ -151,6 +153,8 @@ static FLAC__bool bitreader_read_from_client_(FLAC__BitReader *br)
 
 	/* first shift the unconsumed buffer data toward the front as much as possible */
 	if(br->consumed_words > 0) {
+		crc16_update_block_(br); /* CRC consumed words */
+
 		start = br->consumed_words;
 		end = br->words + (br->bytes? 1:0);
 		memmove(br->buffer, br->buffer+start, FLAC__BYTES_PER_WORD * (end - start));
@@ -328,6 +332,7 @@ void FLAC__bitreader_reset_read_crc16(FLAC__BitReader *br, FLAC__uint16 seed)
 	FLAC__ASSERT((br->consumed_bits & 7) == 0);
 
 	br->read_crc16 = (uint32_t)seed;
+	br->crc16_offset = br->consumed_words;
 	br->crc16_align = br->consumed_bits;
 }
 
@@ -335,6 +340,10 @@ FLAC__uint16 FLAC__bitreader_get_read_crc16(FLAC__BitReader *br)
 {
 	FLAC__ASSERT(0 != br);
 	FLAC__ASSERT(0 != br->buffer);
+
+	/* CRC consumed words up to here */
+	crc16_update_block_(br);
+
 	FLAC__ASSERT((br->consumed_bits & 7) == 0);
 	FLAC__ASSERT(br->crc16_align <= br->consumed_bits);
 
@@ -397,7 +406,6 @@ FLAC__bool FLAC__bitreader_read_raw_uint32(FLAC__BitReader *br, FLAC__uint32 *va
 			/* (FLAC__BITS_PER_WORD - br->consumed_bits <= bits) ==> (FLAC__WORD_ALL_ONES >> br->consumed_bits) has no more than 'bits' non-zero bits */
 			*val = (FLAC__uint32)(word & (FLAC__WORD_ALL_ONES >> br->consumed_bits));
 			bits -= n;
-			crc16_update_word_(br, word);
 			br->consumed_words++;
 			br->consumed_bits = 0;
 			if(bits) { /* if there are still bits left to read, there have to be less than 32 so they will all be in the next word */
@@ -416,7 +424,6 @@ FLAC__bool FLAC__bitreader_read_raw_uint32(FLAC__BitReader *br, FLAC__uint32 *va
 			}
 			/* at this point bits == FLAC__BITS_PER_WORD == 32; because of previous assertions, it can't be larger */
 			*val = (FLAC__uint32)word;
-			crc16_update_word_(br, word);
 			br->consumed_words++;
 			return true;
 		}
@@ -663,7 +670,6 @@ FLAC__bool FLAC__bitreader_read_unary_unsigned(FLAC__BitReader *br, uint32_t *va
 				i++;
 				br->consumed_bits += i;
 				if(br->consumed_bits >= FLAC__BITS_PER_WORD) { /* faster way of testing if(br->consumed_bits == FLAC__BITS_PER_WORD) */
-					crc16_update_word_(br, br->buffer[br->consumed_words]);
 					br->consumed_words++;
 					br->consumed_bits = 0;
 				}
@@ -671,7 +677,6 @@ FLAC__bool FLAC__bitreader_read_unary_unsigned(FLAC__BitReader *br, uint32_t *va
 			}
 			else {
 				*val += FLAC__BITS_PER_WORD - br->consumed_bits;
-				crc16_update_word_(br, br->buffer[br->consumed_words]);
 				br->consumed_words++;
 				br->consumed_bits = 0;
 				/* didn't find stop bit yet, have to keep going... */
@@ -789,7 +794,7 @@ FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[
 			x = ucbits;
 			do {
 				/* didn't find stop bit yet, have to keep going... */
-				crc16_update_word_(br, br->buffer[cwords++]);
+				cwords++;
 				if (cwords >= words)
 					goto incomplete_msbs;
 				b = br->buffer[cwords];
@@ -809,7 +814,7 @@ FLAC__bool FLAC__bitreader_read_rice_signed_block(FLAC__BitReader *br, int vals[
 			b <<= parameter;
 		} else {
 			/* there are still bits left to read, they will all be in the next word */
-			crc16_update_word_(br, br->buffer[cwords++]);
+			cwords++;
 			if (cwords >= words)
 				goto incomplete_lsbs;
 			b = br->buffer[cwords];
@@ -865,7 +870,7 @@ incomplete_lsbs:
 
 	if(ucbits == 0 && cwords < words) {
 		/* don't leave the head word with no unconsumed bits */
-		crc16_update_word_(br, br->buffer[cwords++]);
+		cwords++;
 		ucbits = FLAC__BITS_PER_WORD;
 	}
 
diff --git a/src/libFLAC/crc.c b/src/libFLAC/crc.c
index cb08f137..faa34965 100644
--- a/src/libFLAC/crc.c
+++ b/src/libFLAC/crc.c
@@ -394,3 +394,43 @@ FLAC__uint16 FLAC__crc16(const FLAC__byte *data, uint32_t len)
 
 	return crc;
 }
+
+FLAC__uint16 FLAC__crc16_update_words32(const FLAC__uint32 *words, uint32_t len, FLAC__uint16 crc)
+{
+	while (len >= 2) {
+		crc ^= words[0] >> 16;
+
+		crc = FLAC__crc16_table[7][crc >> 8               ] ^ FLAC__crc16_table[6][crc & 0xFF             ] ^
+		      FLAC__crc16_table[5][(words[0] >>  8) & 0xFF] ^ FLAC__crc16_table[4][ words[0]        & 0xFF] ^
+		      FLAC__crc16_table[3][ words[1] >> 24        ] ^ FLAC__crc16_table[2][(words[1] >> 16) & 0xFF] ^
+		      FLAC__crc16_table[1][(words[1] >>  8) & 0xFF] ^ FLAC__crc16_table[0][ words[1]        & 0xFF];
+
+		words += 2;
+		len -= 2;
+	}
+
+	if (len) {
+		crc ^= words[0] >> 16;
+
+		crc = FLAC__crc16_table[3][crc >> 8               ] ^ FLAC__crc16_table[2][crc & 0xFF             ] ^
+		      FLAC__crc16_table[1][(words[0] >>  8) & 0xFF] ^ FLAC__crc16_table[0][words[0]         & 0xFF];
+	}
+
+	return crc;
+}
+
+FLAC__uint16 FLAC__crc16_update_words64(const FLAC__uint64 *words, uint32_t len, FLAC__uint16 crc)
+{
+	while (len--) {
+		crc ^= words[0] >> 48;
+
+		crc = FLAC__crc16_table[7][crc >> 8               ] ^ FLAC__crc16_table[6][crc & 0xFF             ] ^
+		      FLAC__crc16_table[5][(words[0] >> 40) & 0xFF] ^ FLAC__crc16_table[4][(words[0] >> 32) & 0xFF] ^
+		      FLAC__crc16_table[3][(words[0] >> 24) & 0xFF] ^ FLAC__crc16_table[2][(words[0] >> 16) & 0xFF] ^
+		      FLAC__crc16_table[1][(words[0] >>  8) & 0xFF] ^ FLAC__crc16_table[0][ words[0]        & 0xFF];
+
+		words++;
+	}
+
+	return crc;
+}
diff --git a/src/libFLAC/include/private/crc.h b/src/libFLAC/include/private/crc.h
index 8d3d456b..5fc7e5ee 100644
--- a/src/libFLAC/include/private/crc.h
+++ b/src/libFLAC/include/private/crc.h
@@ -54,5 +54,7 @@ extern FLAC__uint16 const FLAC__crc16_table[8][256];
 #endif
 
 FLAC__uint16 FLAC__crc16(const FLAC__byte *data, uint32_t len);
+FLAC__uint16 FLAC__crc16_update_words32(const FLAC__uint32 *words, uint32_t len, FLAC__uint16 crc);
+FLAC__uint16 FLAC__crc16_update_words64(const FLAC__uint64 *words, uint32_t len, FLAC__uint16 crc);
 
 #endif