112 lines
3.9 KiB
C
112 lines
3.9 KiB
C
#include <stdint.h>
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#include <stdio.h>
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#include "internal.h"
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#include "hammer.h"
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#include "test_suite.h"
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#define LSB(range) (0:range)
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#define MSB(range) (1:range)
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#define LDB(range,i) (((i)>>LSB(range))&((1<<(MSB(range)-LSB(range)+1))-1))
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long long read_bits(input_stream_t* state, int count, char signed_p) {
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long long out = 0;
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int offset = 0;
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long long msb = (!!signed_p) << (count - 1); // 0 if unsigned, else 1 << (nbits - 1)
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while (count) {
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int segment, segment_len;
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// Read a segment...
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if (state->endianness & BIT_BIG_ENDIAN) {
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if (count >= state->bit_offset) {
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segment_len = state->bit_offset;
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state->bit_offset = 8;
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segment = state->input[state->index] & ((1 << segment_len) - 1);
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state->index++;
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} else {
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segment_len = count;
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state->bit_offset -= count;
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segment = (state->input[state->index] >> state->bit_offset) & ((1 << segment_len) - 1);
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}
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} else { // BIT_LITTLE_ENDIAN
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if (count + state->bit_offset >= 8) {
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segment_len = 8 - state->bit_offset;
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segment = (state->input[state->index] >> state->bit_offset);
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state->index++;
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state->bit_offset = 0;
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} else {
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segment_len = count;
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segment = (state->input[state->index] >> state->bit_offset) & ((1 << segment_len) - 1);
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state->bit_offset += segment_len;
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}
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}
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// have a valid segment; time to assemble the byte
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if (state->endianness & BYTE_BIG_ENDIAN) {
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out = out << segment_len | segment;
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} else { // BYTE_LITTLE_ENDIAN
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out |= segment << offset;
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offset += segment_len;
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}
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count -= segment_len;
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}
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return (out ^ msb) - msb; // perform sign extension
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}
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#ifdef INCLUDE_TESTS
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#define MK_INPUT_STREAM(buf,len,endianness_) \
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{ \
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.input = buf, \
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.length = len, \
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.index = 0, \
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.bit_offset = (((endianness_) & BIT_BIG_ENDIAN) ? 8 : 0), \
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.endianness = endianness_ \
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}
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static void test_bitreader_be(void) {
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input_stream_t is = MK_INPUT_STREAM("\x6A\x5A", 2, BIT_BIG_ENDIAN | BYTE_BIG_ENDIAN);
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g_check_cmpint(read_bits(&is, 3, false), ==, 0x03);
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g_check_cmpint(read_bits(&is, 8, false), ==, 0x52);
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g_check_cmpint(read_bits(&is, 5, false), ==, 0x1A);
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}
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static void test_bitreader_le(void) {
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input_stream_t is = MK_INPUT_STREAM("\x6A\x5A", 2, BIT_LITTLE_ENDIAN | BYTE_LITTLE_ENDIAN);
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g_check_cmpint(read_bits(&is, 3, false), ==, 0x02);
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g_check_cmpint(read_bits(&is, 8, false), ==, 0x4D);
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g_check_cmpint(read_bits(&is, 5, false), ==, 0x0B);
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}
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static void test_largebits_be(void) {
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input_stream_t is = MK_INPUT_STREAM("\x6A\x5A", 2, BIT_BIG_ENDIAN | BYTE_BIG_ENDIAN);
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g_check_cmpint(read_bits(&is, 11, false), ==, 0x352);
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g_check_cmpint(read_bits(&is, 5, false), ==, 0x1A);
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}
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static void test_largebits_le(void) {
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input_stream_t is = MK_INPUT_STREAM("\x6A\x5A", 2, BIT_LITTLE_ENDIAN | BYTE_LITTLE_ENDIAN);
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g_check_cmpint(read_bits(&is, 11, false), ==, 0x26A);
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g_check_cmpint(read_bits(&is, 5, false), ==, 0x0B);
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}
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static void test_offset_largebits_be(void) {
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input_stream_t is = MK_INPUT_STREAM("\x6A\x5A", 2, BIT_BIG_ENDIAN | BYTE_BIG_ENDIAN);
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g_check_cmpint(read_bits(&is, 5, false), ==, 0xD);
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g_check_cmpint(read_bits(&is, 11, false), ==, 0x25A);
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}
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static void test_offset_largebits_le(void) {
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input_stream_t is = MK_INPUT_STREAM("\x6A\x5A", 2, BIT_LITTLE_ENDIAN | BYTE_LITTLE_ENDIAN);
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g_check_cmpint(read_bits(&is, 5, false), ==, 0xA);
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g_check_cmpint(read_bits(&is, 11, false), ==, 0x2D3);
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}
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void register_bitreader_tests(void) {
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g_test_add_func("/core/bitreader/be", test_bitreader_be);
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g_test_add_func("/core/bitreader/le", test_bitreader_le);
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g_test_add_func("/core/bitreader/largebits-be", test_largebits_be);
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g_test_add_func("/core/bitreader/largebits-le", test_largebits_le);
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g_test_add_func("/core/bitreader/offset-largebits-be", test_offset_largebits_be);
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g_test_add_func("/core/bitreader/offset-largebits-le", test_offset_largebits_le);
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}
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#endif // #ifdef INCLUDE_TESTS
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