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/* { dg-do compile } */
/* { dg-options "-fdump-tree-crc" } */
/* { dg-skip-if "" { *-*-* } { "-O0" "-O1" "-Os" "-flto" } } */
/* We don't detect this case, because there are many conditional branches.
Even if we detected it won't be verified,
because we would get more than two execution paths (states). */
#include <stdint.h>
typedef uint8_t byte;
byte Compute_CRC8_Simple_OneByte_ShiftReg (byte byteVal)
{
const byte generator = 0x1D;
byte crc = 0; /* init crc register with 0 */
byte b = byteVal;
for (int i = 7; i >= 0; i--)
{
/* check if MSB is set */
if ((crc & 0x80) != 0)
{ /* MSB set, shift it out of the register */
crc = (byte) (crc << 1);
/* shift in next bit of input stream:
* If it's 1, set LSB of crc to 1.
* If it's 0, set LSB of crc to 0. */
crc = ((byte) (b & (1 << i)) != 0) ? (byte) (crc | 0x01)
: (byte) (crc & 0xFE);
/* Perform the 'division' by XORing the crc register with the generator polynomial */
crc = (byte) (crc ^ generator);
}
else
{ /* MSB not set, shift it out and shift in next bit of input stream. Same as above, just no division */
crc = (byte) (crc << 1);
crc = ((byte) (b & (1 << i)) != 0) ? (byte) (crc | 0x01)
: (byte) (crc & 0xFE);
}
}
return crc;
}
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