Port some table-generating stuff from unjpeg.

[fjl] / dehuff_test.c

diff --git a/dehuff_test.c b/dehuff_test.c
new file mode 100644 (file)
index 0000000..e383a1d
--- /dev/null
+++ b/dehuff_test.c
@@ -0,0 +1,80 @@
+#include <stdio.h>
+#include <string.h>
+#include <assert.h>
+
+#include "dehuff.h"
+
+struct custom_read_userdata {
+       uint8_t* bytes;
+       unsigned bytes_left;
+};
+
+ssize_t custom_read(void* userdata, uint8_t* buf, size_t count)
+{
+       struct custom_read_userdata* ud = (struct custom_read_userdata*)userdata;
+       size_t num_to_read = (ud->bytes_left > count ? count : ud->bytes_left);
+       memcpy(buf, ud->bytes, num_to_read);
+       ud->bytes += num_to_read;
+       ud->bytes_left -= num_to_read;
+       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, 
+
+               // 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,
+
+               // Code words
+               0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b,
+       };
+
+       // Expected results (table K.3)
+       struct {
+               unsigned code_length;
+               unsigned code_word;
+       } expected_table[12] = {
+               { 2, 0x0 },
+               { 3, 0x2 },
+               { 3, 0x3 },
+               { 3, 0x4 },
+               { 3, 0x5 },
+               { 3, 0x6 },
+               { 4, 0xe },
+               { 5, 0x1e },
+               { 6, 0x3e },
+               { 7, 0x7e },
+               { 8, 0xfe },
+               { 9, 0x1fe },
+       };
+
+       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 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);
+       }
+}
+
+int main(void)
+{
+       printf("test_table_gen()\n");
+       test_table_gen();
+       
+       printf("All tests pass.\n");
+       return 0;
+}