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Feature/improved bitstream efficiency #66

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69 changes: 52 additions & 17 deletions src/input/code_templates/c/static_code/exi_bitstream.c.jinja
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Original file line number Diff line number Diff line change
Expand Up @@ -165,21 +165,38 @@ int exi_bitstream_write_bits(exi_bitstream_t* stream, size_t bit_count, uint32_t
return EXI_ERROR__BIT_COUNT_LARGER_THAN_TYPE_SIZE;
}

int error = EXI_ERROR__NO_ERROR;
const size_t remaining_bits = 8 - stream->bit_count;
if (remaining_bits >= bit_count)
{
stream->data[stream->byte_pos] |= (uint8_t)((value << (remaining_bits - bit_count)));
stream->bit_count += bit_count;
return EXI_ERROR__NO_ERROR;
}
stream->data[stream->byte_pos] |=
((uint8_t)(value >> (bit_count - remaining_bits)) & (0xff >> stream->bit_count));

for (size_t n = 0; n < bit_count; n++)
bit_count = (bit_count - (8 - stream->bit_count));
if ((stream->byte_pos) >= stream->data_size)
{
uint8_t bit;
bit = (value & (1u << (bit_count - n - 1))) > 0;
return EXI_ERROR__BYTE_BUFFER_TOO_SMALL;
}
stream->byte_pos++;
stream->data[stream->byte_pos] = 0;

error = exi_bitstream_write_bit(stream, bit);
if (error != EXI_ERROR__NO_ERROR)
while (bit_count >= EXI_BITSTREAM_MAX_BIT_COUNT)
{
bit_count = (bit_count - EXI_BITSTREAM_MAX_BIT_COUNT);
if ((stream->byte_pos) >= stream->data_size)
{
break;
return EXI_ERROR__BYTE_BUFFER_TOO_SMALL;
}
stream->data[(stream->byte_pos)++] = (uint8_t)(value >> (bit_count));
}

return error;
stream->data[stream->byte_pos] = (uint8_t)value << (8 - bit_count);
stream->bit_count = bit_count;

return EXI_ERROR__NO_ERROR;
}

int exi_bitstream_write_octet(exi_bitstream_t* stream, uint8_t value)
Expand All @@ -196,27 +213,45 @@ int exi_bitstream_read_bits(exi_bitstream_t* stream, size_t bit_count, uint32_t*
return EXI_ERROR__BIT_COUNT_LARGER_THAN_TYPE_SIZE;
}

int error = EXI_ERROR__NO_ERROR;
const size_t remaining_bits = 8 - stream->bit_count;
if (remaining_bits >= bit_count)
{
*value = (uint32_t)((stream->data[stream->byte_pos] >> (remaining_bits - bit_count)) & ((1 << bit_count) - 1));
stream->bit_count += bit_count;
return EXI_ERROR__NO_ERROR;
}
*value = (uint32_t)(stream->data[stream->byte_pos] & ((1 << remaining_bits) - 1));
bit_count = (bit_count - remaining_bits);
stream->bit_count = 8;
if (stream->byte_pos == stream->data_size)
{
return EXI_ERROR__BITSTREAM_OVERFLOW;
}
stream->byte_pos++;
stream->bit_count = 0;

for (size_t n = 0; n < bit_count; n++)
while (bit_count >= 8)
{
uint8_t bit;
error = exi_bitstream_read_bit(stream, &bit);
if (error != EXI_ERROR__NO_ERROR)
*value = (*value << 8) | stream->data[stream->byte_pos];
bit_count -= 8;
if (stream->byte_pos >= stream->data_size)
{
break;
return EXI_ERROR__BITSTREAM_OVERFLOW;
}

*value = (*value << 1u) | bit;
stream->byte_pos++;
}

*value = (*value << bit_count) | (stream->data[stream->byte_pos] >> (8 - bit_count));
stream->bit_count = bit_count;
{%- if add_debug_code == 1 %}

if (stream->status_callback)
{
stream->status_callback(EXI_DEBUG__BITSTREAM_READ_BITS, 0, bit_count, *value);
}
{% endif %}
return error;

return EXI_ERROR__NO_ERROR;
}

int exi_bitstream_read_octet(exi_bitstream_t* stream, uint8_t* value)
Expand Down