X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=dehuff.c;h=5574e27184b8de5961b01f1f76cbf0e27688c89b;hp=a7254692dd4f90deae10bc2fb571baf9952f26bb;hb=HEAD;hpb=f6111465adacc2840f4cd25d55b3017cbf0593b2

diff --git a/dehuff.c b/dehuff.c
index a725469..5574e27 100644
--- a/dehuff.c
+++ b/dehuff.c
@@ -4,40 +4,11 @@
 
 #include "bytesource.h"
 #include "dehuff.h"
+#include "input.h"
 
-void reliable_read(raw_input_func_t* input_func, void* userdata, uint8_t* buf, size_t len)
+void read_huffman_tables(huffman_tables_t* dst, input_func_t* input_func, void* userdata)
 {
-	while (len > 0) {
-		ssize_t bytes_read = input_func(userdata, buf, len);
-		assert(bytes_read <= (ssize_t)len);
-
-		// TODO: We need better error handling here. setjmp()/longjmp()
-		// should hopefully do the trick, but we need to take care for
-		// suspension.
-		if (bytes_read == (ssize_t)-1) {
-			fprintf(stderr, "Input function returned error\n");
-			exit(1);
-		}
-		if (bytes_read == 0) {
-			fprintf(stderr, "Premature EOF\n");
-			exit(1);
-		}
-
-		buf += bytes_read;
-		len -= bytes_read;
-	}
-}
-
-uint16_t read_length(raw_input_func_t* input_func, void* userdata)
-{
-	uint8_t buf[2];
-	reliable_read(input_func, userdata, buf, 2);
-	return (buf[0] << 8) | buf[1];
-}
-
-void read_huffman_tables(huffman_tables_t* dst, raw_input_func_t* input_func, void* userdata)
-{
-	size_t len = read_length(input_func, userdata);
+	size_t len = read_uint16(input_func, userdata);
 	assert(len > 2);
 	len -= 2;
 
@@ -61,7 +32,7 @@ void read_huffman_tables(huffman_tables_t* dst, raw_input_func_t* input_func, vo
 			exit(1);
 		}
 
-		struct huffman_table* tbl = dst[table_class][table_dest];
+		struct huffman_table* tbl = &((*dst)[table_class][table_dest]);
 		if (len < 16) {
 			fprintf(stderr, "Short read for num_codes\n");
 			exit(1);
@@ -143,11 +114,53 @@ void read_huffman_tables(huffman_tables_t* dst, raw_input_func_t* input_func, vo
 				for (unsigned elem = prefix_min; elem < prefix_max; ++elem) {
 					assert(tbl->lookup_table_codes[elem] == DEHUF_SLOW_PATH);
 					assert(tbl->lookup_table_length[elem] == DEHUF_SLOW_PATH);
-					tbl->lookup_table_codes[elem] = k;
+					tbl->lookup_table_codes[elem] = tbl->codes[k];
 					tbl->lookup_table_length[elem] = length;
 				}
 			}
 		}	
+		
+		// Generate the AC lookup tables.
+		for (unsigned i = 0; i < DEHUF_AC_TABLE_SIZE; ++i) {
+			tbl->ac_table_codes[i] = AC_DEHUF_SLOW_PATH;
+
+			int lookup = i >> (DEHUF_AC_TABLE_BITS - DEHUF_TABLE_BITS);
+			int rs = tbl->lookup_table_codes[lookup];
+			unsigned length = tbl->lookup_table_length[lookup];
+			if (rs == DEHUF_SLOW_PATH) {
+				// Not enough bits to decode even the length.
+				continue;
+			}
+			if (rs == 0x00) {
+				// End of block.
+				tbl->ac_table_codes[i] = 0;
+				tbl->ac_table_length[i] = length;
+				tbl->ac_table_skip[i] = 64;
+				continue;
+			}
+			if (rs == 0xf0) {
+				// 16 zero coefficients.
+				tbl->ac_table_codes[i] = 0;
+				tbl->ac_table_length[i] = length;
+				tbl->ac_table_skip[i] = 16;
+				continue;
+			}
+			
+			unsigned r = rs >> 4;
+			unsigned s = rs & 0xf;
+			if (s > DEHUF_AC_TABLE_BITS - length) {
+				// Not enough bits to decode this coefficient.
+				continue;
+			}
+
+			unsigned bits = (i >> (DEHUF_AC_TABLE_BITS - length - s)) & ((1 << s) - 1);
+
+			tbl->ac_table_codes[i] = extend(bits, s);
+			tbl->ac_table_length[i] = length + s;
+			tbl->ac_table_skip[i] = r + 1;
+
+			assert(tbl->ac_table_length[i] <= DEHUF_AC_TABLE_BITS);
+		}	
 	}
 
 	free(buf);