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Added gamma correction to tcl server. #14

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Added gamma correction to tcl server. #14

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27 changes: 23 additions & 4 deletions src/tcl_server.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,24 +16,32 @@ static int spi_fd = -1;
static u8 spi_data_tx[((1 << 16) / 3) * 4 + 5];
static u32 spi_speed_hz = SPI_DEFAULT_SPEED_HZ;

static u8 gamma_table_red[256];
static u8 gamma_table_green[256];
static u8 gamma_table_blue[256];

void tcl_put_pixels(int fd, u8 spi_data_tx[], u16 count, pixel* pixels) {
int i;
pixel* p;
u8* d;
u8 flag;
u8 r, g, b;

d = spi_data_tx;
*d++ = 0;
*d++ = 0;
*d++ = 0;
*d++ = 0;
for (i = 0, p = pixels; i < count; i++, p++) {
flag = (p->r & 0xc0) >> 6 | (p->g & 0xc0) >> 4 | (p->b & 0xc0) >> 2;
r = gamma_table_red[p->r];
g = gamma_table_green[p->g];
b = gamma_table_blue[p->b];

flag = (r & 0xc0) >> 6 | (g & 0xc0) >> 4 | (b & 0xc0) >> 2;
*d++ = ~flag;
*d++ = p->b;
*d++ = p->g;
*d++ = p->r;
*d++ = r;
*d++ = g;
*d++ = b;
}
spi_write(fd, spi_data_tx, d - spi_data_tx);
}
Expand All @@ -45,6 +53,15 @@ void handler(u8 address, u16 count, pixel* pixels) {
tcl_put_pixels(spi_fd, spi_data_tx, count, pixels);
}

void set_gamma(double gamma_red, double gamma_green, double gamma_blue) {
int i;

for(i=0;i<256;i++) {
gamma_table_red[i] = (uint8_t)(pow(i/255.0,gamma_red)*255.0+0.5);
gamma_table_green[i] = (uint8_t)(pow(i/255.0,gamma_green)*255.0+0.5);
gamma_table_blue[i] = (uint8_t)(pow(i/255.0,gamma_blue)*255.0+0.5);
}
}

int main(int argc, char** argv) {
u16 port = OPC_DEFAULT_PORT;
Expand All @@ -57,6 +74,8 @@ int main(int argc, char** argv) {
return 1;
}
fprintf(stderr, "SPI speed: %.2f MHz, ready...\n", spi_speed_hz*1e-6);
/* set gamma correction */
set_gamma(2.2,2.2,2.2);
opc_source s = opc_new_source(port);
while (s >= 0 && opc_receive(s, handler, TIMEOUT_MS));
fprintf(stderr, "Exiting after %d ms of inactivity\n", TIMEOUT_MS);
Expand Down