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