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raadhus_daemon.c
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raadhus_daemon.c
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#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#include <pthread.h>
#define FPS 20
#define LISTEN_PORT 1234
#define MC_GROUP "224.1.1.1"
static pthread_mutex_t screen_mutex = PTHREAD_MUTEX_INITIALIZER;
static pthread_cond_t screen_cond = PTHREAD_COND_INITIALIZER;
/* We always start with 1 output buffer (which is clearing the screen) */
static int ring_buffer_head = 1;
static int ring_buffer_tail = -1;
static const int MAX_PAYLOAD_SIZE = 1472;
#define RING_BUFFER_SIZE 32
#define NUMBER_OF_PIXELS_ON_STRIP 57
#define NUMBER_OF_STRIPS_ON_PORT 4
#define NUMBER_OF_LEDS_ON_PORT (NUMBER_OF_PIXELS_ON_STRIP * NUMBER_OF_STRIPS_ON_PORT * 3)
#define PORTS_IN_USE 8
/* 32 is a nice number. Even though we have a mix of 28 and 24 we just go for 32 */
#define SEGMENT_SIZE 32
#define NUMBER_OF_SEGMENTS 2
#define XRES 56
#define SEGMENT_SIZE_BYTES (NUMBER_OF_PIXELS_ON_STRIP * 3 * SEGMENT_SIZE)
static unsigned char *screens[RING_BUFFER_SIZE][NUMBER_OF_SEGMENTS];
static void map_pixel(int ix, int iy, const unsigned char *in,
unsigned char *out)
{
const unsigned char *p = &in[(ix + iy * XRES) * 3];
out[0] = p[0];
out[1] = p[1];
out[2] = p[2];
}
static const unsigned char seg_maps[NUMBER_OF_SEGMENTS][SEGMENT_SIZE] =
{{12, 13, 14, 15, 16, 17, 18, 19,
20, 21, 22, 23, 24, 25, 26, 27,
28, 29, 30, 31, 32, 33, 34, 35,
36, 37, 38, 39, 40, 41, 42, 42},
{0, 1, 2, 3, 4, 5, 6, 7,
8, 9, 10, 11, 40, 41, 42, 43,
44, 45, 46, 47, 48, 49, 50, 51,
52, 53, 54, 55, 56, 57, 58, 59}
};
static void map_pixels(const unsigned char *in, unsigned char *segments[])
{
int i, ix, segment;
for(segment = 0; segment < NUMBER_OF_SEGMENTS; segment++) {
unsigned char *out = segments[segment];
for (ix = 0; ix < SEGMENT_SIZE;) {
for (i = 0; i < NUMBER_OF_STRIPS_ON_PORT; i++) {
int ix_mapped = seg_maps[segment][ix];
int iy;
/* Run from bottom to top of strip */
for (iy = 0; iy < NUMBER_OF_PIXELS_ON_STRIP; iy += 2) {
map_pixel(ix_mapped, iy, in, out);
out += 3;
}
/* Run from top to bottom of strip */
for (iy = NUMBER_OF_PIXELS_ON_STRIP - 2; iy >= 0;
iy -= 2) {
map_pixel(ix_mapped, iy, in, out);
out += 3;
}
ix++;
}
}
}
}
/*
Maps a buffer to a payload and returns the number of bytes put into the payload
*/
static int payload_buffer(const unsigned char *screen, unsigned char *payload, int controller)
{
int channelOffset = 0, ledMTUCarry = 0, byteCount = 0;
int count = 0;
do {
int payloadIndex = 0;
unsigned char *portCounter;
if (count) {
/* Insert dummy UDP header, which is needed since they apparently
did not bother to implement a full UDP stack and just throw
the header away
*/
memset(payload + payloadIndex, 0, 8);
payload += 8;
}
payload[payloadIndex + 0] = 'Y';
payload[payloadIndex + 1] = 'T';
payload[payloadIndex + 2] = 'K';
payload[payloadIndex + 3] = 'J';
payload[payloadIndex + 4] = controller;
payload[payloadIndex + 5] = 0;
/* Unknown */
payload[payloadIndex + 6] = 0x57;
payload[payloadIndex + 7] = 0x05;
portCounter = &payload[payloadIndex + 8];
*portCounter = 0;
payload[payloadIndex + 9] = 0;
payloadIndex += 10;
/* Now map the pixels */
do {
int bytesLeft, ledsOnPort;
payload[payloadIndex++] = (channelOffset & 0xff);
payload[payloadIndex++] = ((channelOffset >> 8) & 0xff);
bytesLeft = MAX_PAYLOAD_SIZE - payloadIndex;
if (ledMTUCarry) {
ledsOnPort = ledMTUCarry;
} else {
ledsOnPort = NUMBER_OF_LEDS_ON_PORT;
}
if (ledsOnPort > bytesLeft) {
/* Data cannot fit into one "MTU", we need to split it */
ledMTUCarry = ledsOnPort - (bytesLeft - 2);
ledsOnPort = bytesLeft - 2;
channelOffset += ledsOnPort;
} else {
/* The modulus is there to compensate for data that could not fit
into one "MTU"
*/
channelOffset &= ~(2047);
channelOffset += 2048;
ledMTUCarry = 0;
}
(*portCounter)++;
payload[payloadIndex++] = (ledsOnPort & 0xff);
payload[payloadIndex++] = ((ledsOnPort >> 8) & 0xff);
for (; ledsOnPort > 0; ledsOnPort--) {
payload[payloadIndex] = *screen;
screen++;
payloadIndex++;
count++;
}
} while (payloadIndex < MAX_PAYLOAD_SIZE
&& count < NUMBER_OF_LEDS_ON_PORT * PORTS_IN_USE);
payload += payloadIndex;
byteCount += payloadIndex;
} while (count < NUMBER_OF_LEDS_ON_PORT * PORTS_IN_USE);
return byteCount;
}
static void *led_thread(void *data)
{
int sockd;
unsigned char *payload;
struct sockaddr_in my_addr;
/* Allocate plenty */
payload = malloc(15000);
sockd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockd == -1) {
perror("Socket creation error");
return 0;
}
/* Bind the socket to anything */
my_addr.sin_family = AF_INET;
my_addr.sin_addr.s_addr = INADDR_ANY;
my_addr.sin_port = htons(0);
if (bind(sockd, (struct sockaddr *)&my_addr, sizeof(my_addr)) < 0) {
perror("failed to bind socket");
}
while (1) {
int next_buffer, segment;
pthread_mutex_lock(&screen_mutex);
while ((next_buffer =
(ring_buffer_tail + 1) % RING_BUFFER_SIZE) ==
ring_buffer_head) {
pthread_cond_wait(&screen_cond, &screen_mutex);
}
ring_buffer_tail = next_buffer;
for(segment = 0; segment < NUMBER_OF_SEGMENTS; segment++) {
int bytes_mapped =
payload_buffer(screens[ring_buffer_tail][segment], payload, segment + 1);
struct sockaddr_in dest;
dest.sin_family = AF_INET;
dest.sin_addr.s_addr = inet_addr(MC_GROUP);
dest.sin_port = htons(1097);
if (sendto
(sockd, payload, bytes_mapped, 0, (struct sockaddr *)&dest,
sizeof(dest)) < 0) {
/* we don't really care */
perror("failed");
}
}
pthread_mutex_unlock(&screen_mutex);
usleep(1000 * 1000 / FPS);
}
return 0;
}
int main(int argc, char *argv[])
{
/* Buffer used to hold data from clients and the "screen" which is a mapping of the pixels
that fits how the LEDs should receive them */
unsigned char *buffer;
pthread_t tid;
/* We need to hold xres * yres * 3, but just allocate plenty */
const int buffer_size = 15000;
struct sockaddr_in my_addr, client_addr;
socklen_t addrlen;
ssize_t bread;
int sockd;
/* malloc the receiving buffer */
buffer = malloc(buffer_size);
/* malloc all the temporary screens */
{
int i, j;
for(i = 0; i < RING_BUFFER_SIZE; i++) {
for(j = 0; j < NUMBER_OF_SEGMENTS; j++) {
screens[i][j] = calloc(1, SEGMENT_SIZE_BYTES);
}
}
}
sockd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockd == -1) {
perror("Socket creation error");
return -2;
}
/* Start LED thread */
pthread_create(&tid, NULL, led_thread, NULL);
pthread_detach(tid);
/* Bind the socket to our listening port */
my_addr.sin_family = AF_INET;
my_addr.sin_addr.s_addr = INADDR_ANY;
my_addr.sin_port = htons(LISTEN_PORT);
bind(sockd, (struct sockaddr *)&my_addr, sizeof(my_addr));
addrlen = sizeof(client_addr);
while ((bread =
recvfrom(sockd, buffer, buffer_size, 0,
(struct sockaddr *)&client_addr, &addrlen)) >= 0) {
addrlen = sizeof(client_addr);
pthread_mutex_lock(&screen_mutex);
/* Only use the received buffer if output to LEDs is up to speed */
if (ring_buffer_head != ring_buffer_tail) {
map_pixels(buffer, screens[ring_buffer_head]);
ring_buffer_head =
(ring_buffer_head + 1) % RING_BUFFER_SIZE;
pthread_cond_broadcast(&screen_cond);
}
pthread_mutex_unlock(&screen_mutex);
}
return 0;
}