#include <stdlib.h>

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <fcntl.h>
#include <err.h>
#include <errno.h>
#include <math.h>

#include <sys/ioctl.h>
#include <dev/i2c/i2c_io.h>

#define IIC "/dev/iic2"
#define ADR 0x54

int
iic_write(int fd, i2c_addr_t addr, uint8_t *cmd, size_t cmdlen, uint8_t *buf, size_t buflen)
{
i2c_ioctl_exec_t iie;

iie.iie_op = I2C_OP_WRITE_WITH_STOP;
iie.iie_addr = addr;
iie.iie_cmd = cmd;
iie.iie_cmdlen = cmdlen;
iie.iie_buf = buf;
iie.iie_buflen = buflen;

if (ioctl(fd, I2C_IOCTL_EXEC, &iie) == -1)
return errno;
return 0;
}

int
iic_read(int fd, i2c_addr_t addr, uint8_t *cmd, size_t cmdlen, uint8_t *buf, size_t buflen)
{
i2c_ioctl_exec_t iie;

iie.iie_op = I2C_OP_READ_WITH_STOP;
iie.iie_addr = addr;
iie.iie_cmd = cmd;
iie.iie_cmdlen = cmdlen;
iie.iie_buf = buf;
iie.iie_buflen = buflen;

if (ioctl(fd, I2C_IOCTL_EXEC, &iie) == -1)
return errno;
return 0;
}

void rgb(uint8_t *data, int i, int r, int g, int b)
{
if (i >= 0 && i <= 5) {
data += 2;
data[3*i+0] = b;
data[3*i+1] = g;
data[3*i+2] = r;
}
}

static
uint8_t clamp(unsigned long x) {
return x < 0 ? 0 : x > 255 ? 255 : x;
}

void rgbshade(uint8_t *data, int i, int a)
{
if (i >= 0 && i <= 5) {
data += 2;
data[3*i+0] = clamp(data[3*i+0] * a / 256);
data[3*i+1] = clamp(data[3*i+1] * a / 256);
data[3*i+2] = clamp(data[3*i+2] * a / 256);
}
}

unsigned long
hsv2rgb(double h, double s, double v)
{
double r, g, b;
double f, p, q, t;
int i;

i = (int)floor(h * 6);
f = h * 6 - i;
p = v * (1 - s);
q = v * (1 - f * s);
t = v * (1 - (1 - f) * s);
switch (i) {
case 0: r = v; g = t; b = p; break;
case 1: r = q; g = v; b = p; break;
case 2: r = p; g = v; b = t; break;
case 3: r = p; g = q; b = v; break;
case 4: r = t; g = p; b = v; break;
case 5: r = v; g = p; b = q; break;
}

return
((int)round(r * 255)) << 24 |
((int)round(g * 255)) << 16 |
((int)round(b * 255));
}

int main()
{
int fd, i, k, p;
uint8_t data[] = {
0x00,
0x01,
0x00, 0x00, 0x00,
0x00, 0x00, 0x00,
0x00, 0x00, 0x00,
0x00, 0x00, 0x00,
0x00, 0x00, 0x00,
0x00, 0x00, 0x00,
0x3f, 0x3f, 0x3f,
0x00
};
uint8_t reset[] = {
0x17,
0x00
};

fd = open(IIC, O_RDWR);
if (fd == -1)
err(1,"open %s",IIC);

p = 0;
for (k=0; k<=144; ++k) {
for (i=0; i<6; ++i) {
double hue;
unsigned long pix;
int r,g,b;

hue = (6 * i + p) % 36 / 36.0;

pix = hsv2rgb(hue, 1.0, 1.0);

r = (pix >> 24) & 0xff;
g = (pix >> 16) & 0xff;
b = (pix >> 0) & 0xff;
rgb(data, i, r, g, b);
}
p = (p+1) % 144;

iic_write(fd, ADR, NULL, 0, data, sizeof(data));
usleep(100);
}

for (i=0; i<6; ++i)
rgbshade(data, i, 85);
iic_write(fd, ADR, NULL, 0, data, sizeof(data));
// iic_write(fd, ADR, NULL, 0, reset, sizeof(reset));

close(fd);
}