Matthias Blankertz
7ccab40cd6
Add write support to rp2_sd driver. Cleanup standalone-mp3 test tool and add write test mode. Signed-off-by: Matthias Blankertz <matthias@blankertz.org>
31 lines
774 B
C
31 lines
774 B
C
#pragma once
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#include <stddef.h>
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#include <stdint.h>
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inline static uint8_t sd_crc7(size_t len, const uint8_t data[const static len])
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{
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const uint8_t poly = 0b1001;
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uint8_t crc = 0;
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for (size_t pos = 0; pos < len; ++pos) {
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crc ^= data[pos];
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for (int bit = 0; bit < 8; ++bit) {
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crc = (crc << 1) ^ ((crc & 0x80) ? (poly << 1) : 0);
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}
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}
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return crc >> 1;
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}
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inline static uint16_t sd_crc16(size_t len, const uint8_t data[const static len])
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{
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const uint16_t poly = 0b1000000100001;
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uint16_t crc = 0;
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for (size_t pos = 0; pos < len; ++pos) {
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crc ^= data[pos] << 8;
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for (int bit = 0; bit < 8; ++bit) {
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crc = (crc << 1) ^ ((crc & 0x8000) ? poly : 0);
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}
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}
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return crc;
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}
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