102 lines
3.3 KiB
C
102 lines
3.3 KiB
C
#ifndef _PPST_STREAMFILE_H_
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#define _PPST_STREAMFILE_H_
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#include "../streamfile.h"
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typedef struct {
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off_t start_physical_offset; /* interleaved data start, for this substream */
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size_t interleave_block_size; /* max size that can be read before encountering other substreams */
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size_t stride_size; /* step size between interleave blocks (interleave*channels) */
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size_t stream_size; /* final size of the deinterleaved substream */
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} ppst_io_data;
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/* Handles deinterleaving of complete files, skipping portions or other substreams. */
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static size_t ppst_io_read(STREAMFILE *streamfile, uint8_t *dest, off_t offset, size_t length, ppst_io_data* data) {
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size_t total_read = 0;
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while (length > 0) {
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size_t to_read;
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size_t length_available;
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off_t block_num;
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off_t intrablock_offset;
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off_t physical_offset;
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if (offset >= data->stream_size)
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return total_read;
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block_num = offset / data->interleave_block_size;
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intrablock_offset = offset % data->interleave_block_size;
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physical_offset = data->start_physical_offset + block_num*data->stride_size + intrablock_offset;
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length_available = data->interleave_block_size - intrablock_offset;
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if (length_available > data->stream_size - offset)
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length_available = data->stream_size - offset;
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if (length < length_available) {
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to_read = length;
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}
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else {
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to_read = length_available;
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}
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if (to_read > 0) {
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size_t bytes_read;
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bytes_read = read_streamfile(dest, physical_offset, to_read, streamfile);
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total_read += bytes_read;
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if (bytes_read != to_read) {
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return total_read;
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}
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dest += bytes_read;
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offset += bytes_read;
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length -= bytes_read;
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}
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}
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return total_read;
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}
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static size_t ppst_io_size(STREAMFILE *streamfile, ppst_io_data* data) {
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return data->stream_size;
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}
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static STREAMFILE* setup_ppst_streamfile(STREAMFILE *streamFile, off_t start_offset, size_t interleave_block_size, size_t stride_size, size_t stream_size) {
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STREAMFILE *temp_streamFile = NULL, *new_streamFile = NULL;
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ppst_io_data io_data = {0};
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size_t io_data_size = sizeof(ppst_io_data);
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io_data.start_physical_offset = start_offset;
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io_data.interleave_block_size = interleave_block_size;
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io_data.stride_size = stride_size;
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io_data.stream_size = stream_size;
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/* setup subfile */
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new_streamFile = open_wrap_streamfile(streamFile);
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if (!new_streamFile) goto fail;
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temp_streamFile = new_streamFile;
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new_streamFile = open_io_streamfile(temp_streamFile, &io_data,io_data_size, ppst_io_read,ppst_io_size);
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if (!new_streamFile) goto fail;
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temp_streamFile = new_streamFile;
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new_streamFile = open_buffer_streamfile(new_streamFile,0);
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if (!new_streamFile) goto fail;
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temp_streamFile = new_streamFile;
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new_streamFile = open_fakename_streamfile(temp_streamFile, NULL,"at3");
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if (!new_streamFile) goto fail;
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temp_streamFile = new_streamFile;
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return temp_streamFile;
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fail:
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close_streamfile(temp_streamFile);
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return NULL;
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}
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#endif /* _SCD_STREAMFILE_H_ */
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