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#include <stdint.h>
#ifndef SHIFT_COUNTER_BITS
#error SHIFT_COUNTER_BITS must be defined as 4 (for simulation) or 18 (for hardware bitstreams)!
#endif
void output(uint8_t c)
{
*(volatile char*)0x10000000 = c;
}
uint8_t gray_encode_simple(uint8_t c)
{
return c ^ (c >> 1);
}
uint8_t gray_encode_bitwise(uint8_t c)
{
unsigned int in_buf = c, out_buf = 0, bit = 1;
for (int i = 0; i < 8; i++) {
if ((in_buf & 1) ^ ((in_buf >> 1) & 1))
out_buf |= bit;
in_buf = in_buf >> 1;
bit = bit << 1;
}
return out_buf;
}
uint8_t gray_decode(uint8_t c)
{
uint8_t t = c >> 1;
while (t) {
c = c ^ t;
t = t >> 1;
}
return c;
}
void gray(uint8_t c)
{
uint8_t gray_simple = gray_encode_simple(c);
uint8_t gray_bitwise = gray_encode_bitwise(c);
uint8_t gray_decoded = gray_decode(gray_simple);
if (gray_simple != gray_bitwise || gray_decoded != c)
while (1) asm volatile ("ebreak");
output(101);
}
void main()
{
while (1)
output(0xAA);
}
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