winamp/Src/nsmkv/Lacing.cpp

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2024-09-24 12:54:57 +00:00
#include "Lacing.h"
#include "Cluster.h"
#include "vint.h"
bool nsmkv::Lacing::GetState(uint8_t flags, const uint8_t *data, size_t data_len, nsmkv::LacingState *state)
{
// TODO: error check by making sure data_len doesn't go below 0
switch(flags & BlockBinary::LACE_MASK)
{
case BlockBinary::NO_LACING:
state->laces = 1;
state->positions[0] = 0;
state->sizes[0] = data_len;
#ifdef WA_VALIDATE
printf(" Lacing = NO_LACING\n");
#endif
return true;
case BlockBinary::EBML_LACING:
{
uint16_t number_of_frames = state->laces = *data++ + 1;
uint64_t delta = vint_get_number_bytes(data[0]);
state->sizes[0] = vint_read_ptr_len((uint8_t)delta, data);
delta++;
state->positions[0] = 1;
state->positions[1] = 1+state->sizes[0];
for (uint16_t i=1;i<number_of_frames-1;i++)
{
uint8_t this_len = vint_get_number_bytes(data[delta]);
state->sizes[i] = vsint_read_ptr_len(this_len, data+delta);
state->sizes[i] += state->sizes[i-1];
state->positions[i+1] = state->positions[i] + state->sizes[i];
delta+=this_len + 1;
}
state->sizes[number_of_frames-1] = data_len - state->positions[number_of_frames-1] - delta;
for (uint16_t i=0;i<number_of_frames;i++)
{
state->positions[i] += delta;
}
#ifdef WA_VALIDATE
printf(" Lacing = EBML_LACING\n");
#endif
}
return true;
case BlockBinary::XIPH_LACING:
{
const uint8_t *orig_data = data;
uint16_t number_of_frames=state->laces = *data++ + 1;
for (uint16_t i=0;i!=number_of_frames-1;i++)
{
size_t frame_len = 0;
do
{
frame_len += *data;
} while (data && *data++ == 255);
state->sizes[i] = frame_len;
}
uint64_t delta = data - orig_data;
uint64_t last_position = delta;
uint64_t last_size = 0;
for (uint16_t i=0;i!=number_of_frames;i++)
{
state->positions[i] = last_position + last_size;
last_position = state->positions[i];
last_size = state->sizes[i];
}
state->sizes[number_of_frames-1] = data_len - state->positions[number_of_frames-1];
#ifdef WA_VALIDATE
printf(" Lacing = XIPH LACING\n");
#endif
}
return true;
case BlockBinary::FIXED_LACING:
{
uint16_t number_of_frames=state->laces=data[0]+1;
uint32_t size_per_frame = (uint32_t)(data_len-1) / number_of_frames;
for (uint16_t i=0;i<number_of_frames;i++)
{
state->positions[i] = (uint64_t)(1 + size_per_frame*i);
state->sizes[i] = size_per_frame;
}
#ifdef WA_VALIDATE
printf(" Lacing = FIXED LACING\n");
#endif
}
return true;
default:
return false;
}
}
bool nsmkv::Lacing::GetFrame(uint16_t frame_number, const uint8_t *data, size_t data_len, const uint8_t **frame, size_t *frame_len, const LacingState *state)
{
if (frame_number >= state->laces)
return false;
const uint8_t *lace = data + state->positions[frame_number];
size_t lace_len = (size_t)state->sizes[frame_number];
if (lace < data // if the lace starts before our data
|| (state->positions[frame_number] + lace_len) > data_len) // or extends out past our data
{
return false;
}
*frame = lace;
*frame_len = lace_len;
return true;
}