X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=dehuff.c;h=0a9fbbcf1a4bcf1b2eb9f413eca7f1784503397e;hp=3e0fd6c4ec86ab441ca36c921cb134d1cf842228;hb=618548d1f2e076a3da21368e708cf887dcbd20d2;hpb=47de6c270a336574dce220cde780a802a513d113

diff --git a/dehuff.c b/dehuff.c
index 3e0fd6c..0a9fbbc 100644
--- a/dehuff.c
+++ b/dehuff.c
@@ -121,7 +121,53 @@ void read_huffman_tables(huffman_tables_t* dst, raw_input_func_t* input_func, vo
 			j += tbl->num_codes[i];
 			tbl->maxcode[i] = tbl->huffcode[j - 1];
 		}
+
+		// Generate the lookup tables
+		for (unsigned i = 0; i < DEHUF_TABLE_SIZE; ++i) {
+			tbl->lookup_table_codes[i] = DEHUF_SLOW_PATH;
+			tbl->lookup_table_length[i] = DEHUF_SLOW_PATH;
+		}
+	
+		unsigned k = 0;	
+		for (unsigned i = 0; i < 16; ++i) {
+			for (unsigned j = 0; j < tbl->num_codes[i]; ++j, ++k) {
+				const unsigned code = tbl->huffcode[k];
+				const unsigned length = tbl->huffsize[k];
+				if (length > DEHUF_TABLE_BITS) {
+					continue;
+				}
+				const unsigned prefix_min = code << (DEHUF_TABLE_BITS - length);
+				const unsigned prefix_max = ((code + 1) << (DEHUF_TABLE_BITS - length));
+
+				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_length[elem] = length;
+				}
+			}
+		}	
 	}
 
 	free(buf);
 }
+
+unsigned read_huffman_symbol_slow_path(const struct huffman_table* table,
+                                       struct bit_source* source) {
+	possibly_refill(source, 1);
+	unsigned code = read_bits(source, 1);
+	int i = 0;
+
+	while (code > table->maxcode[i] || table->maxcode[i] == -1) {
+		possibly_refill(source, 1);
+		code = (code << 1) | read_bits(source, 1);
+		++i;
+
+		if (i > 15) {
+			fprintf(stderr, "Error in Huffman decoding: Too long code (%x)\n", code);
+			exit(1);
+		}
+	}
+
+	return table->codes[table->valptr[i] + code - table->mincode[i]];
+}