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failing CRC7 implementation

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This commit is contained in:
soypat
2024-01-14 14:17:04 -03:00
parent 2f85c8bd04
commit 46cd56951c
4 changed files with 198 additions and 76 deletions
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sd/definitions.go
+49 -15
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@@ -196,6 +196,15 @@ func (c *CSD) DeviceCapacity() (size uint64) {
return size
}
// NumberOfBlocks returns amount of readable blocks in the device given by Capacity/ReadBlockLength.
func (c *CSD) NumberOfBlocks() (numBlocks uint64) {
rblocks := c.ReadBlockLen()
if rblocks == 0 {
return 0
}
return c.DeviceCapacity() / uint64(rblocks)
}
// After byte 5 CSDv1 and CSDv2 differ in structure at some fields.
// DeviceCapacity returns the device capacity in bytes.
@@ -440,9 +449,9 @@ func b2u8(b bool) uint8 {
}
// CRC16 computes the CRC16 checksum for a given payload using the CRC-16-CCITT polynomial.
func CRC16(buf []byte) (sum uint16) {
func CRC16(buf []byte) (crc uint16) {
const poly uint16 = 0x1021 // Generator polynomial G(x) = x^16 + x^12 + x^5 + 1
var crc uint16 = 0x0000 // Initial value
for _, b := range buf {
crc ^= (uint16(b) << 8) // Shift byte into MSB of crc
for i := 0; i < 8; i++ { // Process each bit
@@ -457,19 +466,44 @@ func CRC16(buf []byte) (sum uint16) {
}
// CRC7 computes the CRC7 checksum for a given payload using the polynomial x^7 + x^3 + 1.
func CRC7(data []byte) uint8 {
const poly uint8 = 0x09 // Generator polynomial G(x) = x^7 + x^3 + 1
var crc uint8 = 0x00 // Initial value
func CRC7(data []byte) (crc uint8) {
for _, b := range data {
crc ^= b // Initial XOR
for i := 0; i < 8; i++ { // Process each bit
if crc&0x80 != 0 {
crc = (crc << 1) ^ poly
} else {
crc <<= 1
}
}
crc = crc7_table[crc^b]
}
return crc >> 1
return crc
}
var crc7_table = [256]byte{
0x00, 0x12, 0x24, 0x36, 0x48, 0x5a, 0x6c, 0x7e,
0x90, 0x82, 0xb4, 0xa6, 0xd8, 0xca, 0xfc, 0xee,
0x32, 0x20, 0x16, 0x04, 0x7a, 0x68, 0x5e, 0x4c,
0xa2, 0xb0, 0x86, 0x94, 0xea, 0xf8, 0xce, 0xdc,
0x64, 0x76, 0x40, 0x52, 0x2c, 0x3e, 0x08, 0x1a,
0xf4, 0xe6, 0xd0, 0xc2, 0xbc, 0xae, 0x98, 0x8a,
0x56, 0x44, 0x72, 0x60, 0x1e, 0x0c, 0x3a, 0x28,
0xc6, 0xd4, 0xe2, 0xf0, 0x8e, 0x9c, 0xaa, 0xb8,
0xc8, 0xda, 0xec, 0xfe, 0x80, 0x92, 0xa4, 0xb6,
0x58, 0x4a, 0x7c, 0x6e, 0x10, 0x02, 0x34, 0x26,
0xfa, 0xe8, 0xde, 0xcc, 0xb2, 0xa0, 0x96, 0x84,
0x6a, 0x78, 0x4e, 0x5c, 0x22, 0x30, 0x06, 0x14,
0xac, 0xbe, 0x88, 0x9a, 0xe4, 0xf6, 0xc0, 0xd2,
0x3c, 0x2e, 0x18, 0x0a, 0x74, 0x66, 0x50, 0x42,
0x9e, 0x8c, 0xba, 0xa8, 0xd6, 0xc4, 0xf2, 0xe0,
0x0e, 0x1c, 0x2a, 0x38, 0x46, 0x54, 0x62, 0x70,
0x82, 0x90, 0xa6, 0xb4, 0xca, 0xd8, 0xee, 0xfc,
0x12, 0x00, 0x36, 0x24, 0x5a, 0x48, 0x7e, 0x6c,
0xb0, 0xa2, 0x94, 0x86, 0xf8, 0xea, 0xdc, 0xce,
0x20, 0x32, 0x04, 0x16, 0x68, 0x7a, 0x4c, 0x5e,
0xe6, 0xf4, 0xc2, 0xd0, 0xae, 0xbc, 0x8a, 0x98,
0x76, 0x64, 0x52, 0x40, 0x3e, 0x2c, 0x1a, 0x08,
0xd4, 0xc6, 0xf0, 0xe2, 0x9c, 0x8e, 0xb8, 0xaa,
0x44, 0x56, 0x60, 0x72, 0x0c, 0x1e, 0x28, 0x3a,
0x4a, 0x58, 0x6e, 0x7c, 0x02, 0x10, 0x26, 0x34,
0xda, 0xc8, 0xfe, 0xec, 0x92, 0x80, 0xb6, 0xa4,
0x78, 0x6a, 0x5c, 0x4e, 0x30, 0x22, 0x14, 0x06,
0xe8, 0xfa, 0xcc, 0xde, 0xa0, 0xb2, 0x84, 0x96,
0x2e, 0x3c, 0x0a, 0x18, 0x66, 0x74, 0x42, 0x50,
0xbe, 0xac, 0x9a, 0x88, 0xf6, 0xe4, 0xd2, 0xc0,
0x1c, 0x0e, 0x38, 0x2a, 0x54, 0x46, 0x70, 0x62,
0x8c, 0x9e, 0xa8, 0xba, 0xc4, 0xd6, 0xe0, 0xf2,
}