52 lines
1.1 KiB
C
52 lines
1.1 KiB
C
#include "liblocky.h"
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#include <assert.h>
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bool blky_decoder_feed(blky_decoder_t* de, uint32_t block_index) {
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assert(de->block_num > 0);
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assert(de->feat_bits > 0);
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assert(de->seed > 0);
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const uint64_t seed = blky_numeric_xorshift64(de->seed);
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if (de->count++) {
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const uint32_t feat_max = 1 << de->feat_bits;
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assert(feat_max < de->block_num);
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uint32_t feat = 0;
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for (; feat < feat_max; ++feat) {
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if (blky_numeric_hop(de->block_index, feat, seed)%de->block_num == block_index) {
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break;
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}
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}
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if (feat >= feat_max) return false;
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assert(de->scrap_bits+8 <= 32);
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de->scrap |= feat << de->scrap_bits;
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de->scrap_bits += de->feat_bits;
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}
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de->seed = seed;
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de->block_index = block_index;
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return true;
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}
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bool blky_decoder_pop(blky_decoder_t* de, uint8_t* b, bool force) {
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if (force) {
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if (de->scrap_bits > 0) return false;
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} else {
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if (de->scrap_bits < 8) return false;
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}
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*b = (uint8_t) (de->scrap & 0xFF);
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de->scrap >>= 8;
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if (de->scrap_bits >= 8) {
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de->scrap_bits -= 8;
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} else {
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de->scrap_bits = 0;
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}
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return true;
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}
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