X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=dehuff_test.c;h=eed09520dab288214cf9a57236d4a24197045902;hp=e383a1d5d43911a2a9a2dd7faa9733fd63077032;hb=9069ae93f3e9e9b44f5f28968f508d09f0711737;hpb=47de6c270a336574dce220cde780a802a513d113

diff --git a/dehuff_test.c b/dehuff_test.c
index e383a1d..eed0952 100644
--- a/dehuff_test.c
+++ b/dehuff_test.c
@@ -19,23 +19,36 @@ ssize_t custom_read(void* userdata, uint8_t* buf, size_t count)
 	return num_to_read;	
 }
 
-// Uses the example from section K.3.1 from the JPEG standard.
-void test_table_gen()
-{
-	uint8_t bytes[] = {
-		// Chunk length: Chunk length (2) + coefficient class (1) + 
-		// code lengths (16) + code words (12)
-		0, 31, 
+// The example from section K.3.1 from the JPEG standard.
+uint8_t example_table_bytes[] = {
+	// Chunk length: Chunk length (2) + coefficient class (1) + 
+	// code lengths (16) + code words (12)
+	0, 31, 
 
-		// DC coefficient, table 0
-		0x00,
+	// DC coefficient, table 0
+	0x00,
 
-		// List of code lengths
-		0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+	// List of code lengths
+	0x00, 0x01, 0x05, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
 
-		// Code words
-		0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
-	};
+	// Code words
+	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
+};
+
+void read_example_tables(huffman_tables_t* tables)
+{
+	struct custom_read_userdata ud;
+	ud.bytes = example_table_bytes;
+	ud.bytes_left = sizeof(example_table_bytes);
+
+	read_huffman_tables(tables, custom_read, &ud);
+}	
+
+// Test that the generated code tables are what we expect.
+void test_table_gen()
+{
+	huffman_tables_t tables;
+	read_example_tables(&tables);
 
 	// Expected results (table K.3)
 	struct {
@@ -55,18 +68,72 @@ void test_table_gen()
 		{ 8, 0xfe },
 		{ 9, 0x1fe },
 	};
+	
+	struct huffman_table* tbl = &tables[DC_CLASS][0];	
+	for (unsigned i = 0; i < 12; ++i) {
+		assert(tbl->huffsize[i] == expected_table[i].code_length);
+		assert(tbl->huffcode[i] == expected_table[i].code_word);
+	}
+}
+
+// Test that we can decode a simple bit stream.
+// Note that since we end on a long code, we won't crash into
+// the end-of-stream problems we have without padding.
+void test_decoding()
+{
+	huffman_tables_t tables;
+	read_example_tables(&tables);
+	
+	// Our stream looks like this:
+	//
+	//  0   1   2   3   4   5    6     7      8       9       10        11
+	// 00 010 011 100 101 110 1110 11110 111110 1111110 11111110 111111110
+	uint8_t bytes[] = {
+		0x13, 0x97, 0x77, 0xbe, 0xfd, 0xfd, 0xfe
+	};
 
 	struct custom_read_userdata ud;
 	ud.bytes = bytes;
 	ud.bytes_left = sizeof(bytes);
 
-	huffman_tables_t tables;
-	read_huffman_tables(&tables, custom_read, &ud);
+	struct bit_source source;
+	init_bit_source(&source, custom_read, 0, &ud);
 		
 	struct huffman_table* tbl = &tables[DC_CLASS][0];	
 	for (unsigned i = 0; i < 12; ++i) {
-		assert(tbl->huffsize[i] == expected_table[i].code_length);
-		assert(tbl->huffcode[i] == expected_table[i].code_word);
+		unsigned symbol = read_huffman_symbol(tbl, &source);
+		assert(symbol == i);
+	}
+
+	assert(source.bits_available == 0);
+}
+
+// Test that we can decode a bit stream that ends on a short code,
+// if we've got padding.
+void test_padded_decoding()
+{
+	huffman_tables_t tables;
+	read_example_tables(&tables);
+	
+	// Our stream looks like this:
+	//
+	//  0   1   2   3   4
+	// 00 010 011 100 101
+	uint8_t bytes[] = {
+		0x13, 0x94
+	};
+
+	struct custom_read_userdata ud;
+	ud.bytes = bytes;
+	ud.bytes_left = sizeof(bytes);
+
+	struct bit_source source;
+	init_bit_source(&source, custom_read, 2, &ud);
+		
+	struct huffman_table* tbl = &tables[DC_CLASS][0];	
+	for (unsigned i = 0; i < 5; ++i) {
+		unsigned symbol = read_huffman_symbol(tbl, &source);
+		assert(symbol == i);
 	}
 }
 
@@ -75,6 +142,12 @@ int main(void)
 	printf("test_table_gen()\n");
 	test_table_gen();
 	
+	printf("test_decoding()\n");
+	test_decoding();
+	
+	printf("test_padded_decoding()\n");
+	test_padded_decoding();
+	
 	printf("All tests pass.\n");
 	return 0;
 }