36 lines
938 B
C
36 lines
938 B
C
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#include <stdint.h>
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#include "checksum.h"
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uint16_t checksum(void *buff, uint32_t size)
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{
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uint32_t r2 = 0xffff;
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uint32_t r3 = 0;
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uint32_t i, j;
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for (i=0; i<size; i++) {
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r3 = 0x80;
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for (j=0; j<8; j++) {
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if ((r2 & 0x8000) != 0) {
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r2 <<= 17;
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r2 >>= 16;
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r2 ^= 0x1000;
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r2 ^= 0x21;
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}
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else {
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r2 <<= 17;
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r2 >>= 16;
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}
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if ((((uint8_t *)buff)[i] & r3) != 0) {
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r2 ^= 0x1000;
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r2 ^= 0x21;
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}
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r3 >>= 1;
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}
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}
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return r2 & 0xffff;
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}
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