54 lines
1.5 KiB
C++
54 lines
1.5 KiB
C++
#include "read.h"
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/* helper macro to do a read, check error code and number of bytes read, and return from the function if necessary
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has to be a macro because of the return */
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#define NSAVI_READ(reader, buffer, size, bytes_read) { int ret = reader->Read(buffer, size, &bytes_read); if (ret) return ret; if (bytes_read != size) return READ_EOF; }
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int nsavi::read_riff_chunk(nsavi::avi_reader *reader, nsavi::riff_chunk *chunk, uint32_t *out_bytes_read)
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{
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uint32_t total_bytes_read=0;
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uint32_t bytes_read;
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NSAVI_READ(reader, chunk, 8, bytes_read); // read id and size
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total_bytes_read += bytes_read;
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if (chunk->id == 'FFIR' || chunk->id == 'TSIL')
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{
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if (chunk->size < 4)
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return READ_INVALID_DATA;
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NSAVI_READ(reader, &chunk->type, 4, bytes_read);
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total_bytes_read += bytes_read;
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chunk->size -= 4;
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}
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else
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chunk->type = 0;
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if (out_bytes_read)
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*out_bytes_read = total_bytes_read;
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return READ_OK;
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}
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// we pass riff_chunk instead of size
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// to avoid any confusion about who is responsible for adding the padding byte
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// (this function is responsible)
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int nsavi::skip_chunk(nsavi::avi_reader *reader, const nsavi::riff_chunk *chunk, uint32_t *out_bytes_read)
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{
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uint32_t chunk_size = chunk->size;
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if (chunk_size & 1)
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{
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chunk_size ++; // odd chunk sizes must be padded by one
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if (chunk_size == 0) // check for overflow
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return READ_INVALID_DATA;
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}
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int ret = reader->Skip(chunk_size);
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if (ret)
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return ret;
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if (out_bytes_read)
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*out_bytes_read = chunk_size;
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return READ_OK;
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}
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