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Improvements in icestorm test firmware

This commit is contained in:
Clifford Wolf 2015-07-31 11:08:28 +02:00
parent 484fa4ac5f
commit 2f326d0761
1 changed files with 35 additions and 7 deletions
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42
scripts/icestorm/firmware.c
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@ -1,22 +1,50 @@
#include <stdint.h>
// use SHIFT_COUNTER_BITS=4 for simulation
#define SHIFT_COUNTER_BITS 16
#define SHIFT_COUNTER_BITS 18
void output(uint8_t c)
{
*(volatile char*)0x10000000 = c;
}
void output_gray(uint8_t c)
uint8_t gray_encode_simple(uint8_t c)
{
unsigned int in_buf = c, out_buf = 0;
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++) {
unsigned int bit = (in_buf & 1) ^ ((in_buf >> 1) & 1);
if ((in_buf & 1) ^ ((in_buf >> 1) & 1))
out_buf |= bit;
in_buf = in_buf >> 1;
out_buf = (out_buf << 1) | bit;
bit = bit << 1;
}
output(out_buf);
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 ("sbreak");
output(gray_simple);
}
void main()
@ -24,6 +52,6 @@ void main()
for (uint32_t counter = (2+4+32+64) << SHIFT_COUNTER_BITS;; counter++) {
asm volatile ("" : : "r"(counter));
if ((counter & ~(~0 << SHIFT_COUNTER_BITS)) == 0)
output_gray(counter >> SHIFT_COUNTER_BITS);
gray(counter >> SHIFT_COUNTER_BITS);
}
}