322 lines
11 KiB
C
322 lines
11 KiB
C
/* -------------------------------------------------------------
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* waveform_tcp.c
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*
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* * 600×400 ARGB8888 frame is streamed over a single‑client TCP socket.
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* * The received frame is transformed so that the resulting bitmap
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* can be displayed on a video waveform monitor and will look like
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* the original picture.
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*
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* Build (Linux/macOS):
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* gcc -Wall -Wextra -pedantic -std=c11 waveform_tcp.c \
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* -lSDL2 -lpthread -o waveform_tcp
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*
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* Run:
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* ./waveform_tcp # opens a window and listens on 0.0.0.0:12345
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*
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* Test client (Unix‑like, sends one frame of solid gray):
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* dd if=/dev/zero bs=1 count=$((600*400*4)) | tr \\0 \\377 > gray.bin
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* cat gray.bin | nc 127.0.0.1 12345
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*
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* ------------------------------------------------------------- */
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#include <SDL2/SDL.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <string.h> // memcpy, memset
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#include <unistd.h> // close, read, write
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#include <fcntl.h> // fcntl
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#include <sys/types.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <arpa/inet.h>
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#include <errno.h>
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/* -------------------------------------------------------------
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* Configuration
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* ------------------------------------------------------------- */
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#define WIDTH 800
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#define HEIGHT 600
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#define LISTEN_PORT 12345 // change if you like
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#define BACKLOG 1 // only one pending connection
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/* -------------------------------------------------------------
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* Simple pixel helpers (ARGB8888 – 0xAARRGGBB in memory)
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* ------------------------------------------------------------- */
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typedef Uint32 pixel_t;
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static inline pixel_t make_pixel(Uint8 r, Uint8 g, Uint8 b, Uint8 a)
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{
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return (pixel_t)((a << 24) | (r << 16) | (g << 8) | b);
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}
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#define MAKE_OPAQUE_PIXEL(r,g,b) make_pixel((r),(g),(b),0xFF)
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/* -------------------------------------------------------------
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* Global buffers
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* ------------------------------------------------------------- */
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/* 1. The raw frame received from the network */
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static pixel_t net_frame[HEIGHT][WIDTH];
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/* 2. The image that we actually draw (after the waveform conversion) */
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static pixel_t draw_buf[HEIGHT][WIDTH];
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/* -------------------------------------------------------------
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* Demo pattern – what we see until the first network frame arrives
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* ------------------------------------------------------------- */
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static void init_demo_pattern(void)
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{
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for (int y = 0; y < HEIGHT; ++y) {
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for (int x = 0; x < WIDTH; ++x) {
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Uint8 r = (HEIGHT-y)*255/HEIGHT;//(Uint8)((x * 255) / (WIDTH - 1));
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Uint8 g = (HEIGHT-y)*255/HEIGHT;//(Uint8)((y * 255) / (HEIGHT - 1));
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Uint8 b = (HEIGHT-y)*255/HEIGHT;//0x80;
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draw_buf[y][x] = MAKE_OPAQUE_PIXEL(r, g, b);
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}
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}
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}
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/* -------------------------------------------------------------
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* Luminance conversion – ITU‑BT.601 (Y = 0.299R + 0.587G + 0.114B)
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* ------------------------------------------------------------- */
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static inline Uint8 rgb_to_luma(Uint8 r, Uint8 g, Uint8 b)
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{
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/* weighted sum, integer arithmetic, rounded */
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return (Uint8)((299 * r + 587 * g + 114 * b) / 1000);
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}
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/* -------------------------------------------------------------
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* Transform the raw ARGB frame into a waveform‑ready image.
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*
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* * dest is the global draw_buf
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* * every source pixel (sx, sy) becomes a white dot at
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* dx = sx
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* dy = round( luma * (HEIGHT‑1) / 255 )
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*
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* The whole destination buffer is cleared to black first.
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* ------------------------------------------------------------- */
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static void convert_to_waveform(void)
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{
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const pixel_t WHITE = 0xFFFFFFFFU; /* ARGB = opaque white */
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const pixel_t BLACK = 0xFF000000U; /* opaque black (background) */
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/* 1. clear destination */
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for (int y = 0; y < HEIGHT; ++y)
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memset(draw_buf[y], 0, WIDTH * sizeof(pixel_t));
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for (int y = 0; y < HEIGHT; ++y)
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for (int x = 0; x < WIDTH; ++x)
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draw_buf[y][x] = BLACK;
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/* 2. plot points */
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for (int sy = 0; sy < HEIGHT; ++sy) {
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for (int sx = 0; sx < WIDTH; ++sx) {
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pixel_t p = net_frame[sy][sx];
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Uint8 r = (Uint8)((p >> 16) & 0xFF);
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Uint8 g = (Uint8)((p >> 8) & 0xFF);
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Uint8 b = (Uint8)( p & 0xFF);
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Uint8 luma = rgb_to_luma(r, g, b); /* 0‑255 */
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if(luma >= 150)
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draw_buf[sy][sx] = 0xff<<24 | (255-sy/2) << 16 | (255-sy/2) << 8 | (255-sy/2); /* overwrite – white dot */
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else
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draw_buf[sy][sx] = 0xff<<24;
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//draw_buf[sy][sx] = (255-sy/2)<<24 | 0xFFFFFFU;
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}
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}
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}
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/* -------------------------------------------------------------
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* ---------- TCP SERVER ------------------------------------
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* ------------------------------------------------------------- */
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/* Returns a non‑blocking listening socket, or -1 on error. */
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static int create_listen_socket(void)
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{
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int lst = socket(AF_INET, SOCK_STREAM, 0);
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if (lst < 0) {
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perror("socket");
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return -1;
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}
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int opt = 1;
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setsockopt(lst, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
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struct sockaddr_in addr = {
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.sin_family = AF_INET,
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.sin_port = htons(LISTEN_PORT),
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.sin_addr = { .s_addr = INADDR_ANY }
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};
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if (bind(lst, (struct sockaddr *)&addr, sizeof(addr)) < 0) {
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perror("bind");
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close(lst);
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return -1;
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}
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if (listen(lst, BACKLOG) < 0) {
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perror("listen");
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close(lst);
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return -1;
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}
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/* make non‑blocking */
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int flags = fcntl(lst, F_GETFL, 0);
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fcntl(lst, F_SETFL, flags | O_NONBLOCK);
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printf("[net] Listening on 0.0.0.0:%d (single client allowed)\n", LISTEN_PORT);
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return lst;
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}
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/* Helper – set a socket to non‑blocking mode */
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static void set_nonblocking(int fd)
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{
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int flags = fcntl(fd, F_GETFL, 0);
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if (flags != -1) fcntl(fd, F_SETFL, flags | O_NONBLOCK);
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}
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/* -------------------------------------------------------------
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* MAIN
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* ------------------------------------------------------------- */
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int main(void)
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{
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/* ---------- SDL initialisation -------------------------------- */
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if (SDL_Init(SDL_INIT_VIDEO) != 0) {
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fprintf(stderr, "SDL_Init error: %s\n", SDL_GetError());
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return EXIT_FAILURE;
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}
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SDL_Window *window = SDL_CreateWindow("Waveform‑ready demo (TCP input)",
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SDL_WINDOWPOS_CENTERED,
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SDL_WINDOWPOS_CENTERED,
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WIDTH, HEIGHT,
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SDL_WINDOW_SHOWN);
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if (!window) {
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fprintf(stderr, "SDL_CreateWindow error: %s\n", SDL_GetError());
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SDL_Quit();
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return EXIT_FAILURE;
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}
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SDL_Renderer *renderer = SDL_CreateRenderer(window, -1,
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SDL_RENDERER_ACCELERATED |
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SDL_RENDERER_PRESENTVSYNC);
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if (!renderer) {
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fprintf(stderr, "SDL_CreateRenderer error: %s\n", SDL_GetError());
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SDL_DestroyWindow(window);
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SDL_Quit();
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return EXIT_FAILURE;
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}
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SDL_Texture *texture = SDL_CreateTexture(renderer,
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SDL_PIXELFORMAT_ARGB8888,
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SDL_TEXTUREACCESS_STREAMING,
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WIDTH, HEIGHT);
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if (!texture) {
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fprintf(stderr, "SDL_CreateTexture error: %s\n", SDL_GetError());
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SDL_DestroyRenderer(renderer);
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SDL_DestroyWindow(window);
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SDL_Quit();
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return EXIT_FAILURE;
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}
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/* ---------- Demo pattern (until first network frame) ---------- */
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init_demo_pattern();
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/* ---------- Networking --------------------------------------- */
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int listen_sock = create_listen_socket(); /* may be -1 on failure */
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int client_sock = -1; /* -1 → no client yet */
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const size_t FRAME_BYTES = WIDTH * HEIGHT * sizeof(pixel_t);
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size_t recv_offset = 0; /* bytes already received */
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bool quit = false;
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SDL_Event ev;
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/* ---------- Main loop --------------------------------------- */
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while (!quit) {
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/* 1) SDL events */
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while (SDL_PollEvent(&ev)) {
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if (ev.type == SDL_QUIT) quit = true;
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else if (ev.type == SDL_KEYDOWN && ev.key.keysym.sym == SDLK_ESCAPE)
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quit = true;
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}
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/* 2) Accept a new client if none is present */
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if (listen_sock >= 0 && client_sock < 0) {
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struct sockaddr_in remote;
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socklen_t remote_len = sizeof(remote);
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int tmp = accept(listen_sock,
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(struct sockaddr *)&remote,
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&remote_len);
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if (tmp >= 0) {
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client_sock = tmp;
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set_nonblocking(client_sock);
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recv_offset = 0;
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char ip[INET_ADDRSTRLEN];
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inet_ntop(AF_INET, &remote.sin_addr, ip, sizeof(ip));
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printf("[net] Client connected from %s:%d\n", ip,
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ntohs(remote.sin_port));
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} else if (errno != EAGAIN && errno != EWOULDBLOCK) {
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perror("[net] accept");
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}
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}
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/* 3) Read raw pixel data from the client */
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if (client_sock >= 0) {
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size_t still_needed = FRAME_BYTES - recv_offset;
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ssize_t n = recv(client_sock,
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((Uint8 *)net_frame) + recv_offset,
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still_needed,
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0);
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if (n > 0) {
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recv_offset += (size_t)n;
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if (recv_offset == FRAME_BYTES) {
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/* Full frame received – convert to waveform image */
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convert_to_waveform();
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recv_offset = 0; /* ready for the next frame */
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}
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} else if (n == 0) {
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printf("[net] Client disconnected.\n");
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close(client_sock);
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client_sock = -1;
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} else if (n < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
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perror("[net] recv");
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close(client_sock);
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client_sock = -1;
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}
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}
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/* 4) Copy the (possibly transformed) draw buffer into the texture */
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void *tex_pixels;
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int tex_pitch;
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if (SDL_LockTexture(texture, NULL, &tex_pixels, &tex_pitch) != 0) {
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fprintf(stderr, "SDL_LockTexture error: %s\n", SDL_GetError());
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break;
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}
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for (int y = 0; y < HEIGHT; ++y) {
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memcpy((Uint8 *)tex_pixels + y * tex_pitch,
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draw_buf[y],
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WIDTH * sizeof(pixel_t));
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}
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SDL_UnlockTexture(texture);
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/* 5) Render */
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SDL_RenderClear(renderer);
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SDL_RenderCopy(renderer, texture, NULL, NULL);
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SDL_RenderPresent(renderer);
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/* VSYNC caps the loop to the monitor refresh rate. */
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}
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/* -------------------------------------------------------------
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* Cleanup
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* ------------------------------------------------------------- */
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if (client_sock >= 0) close(client_sock);
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if (listen_sock >= 0) close(listen_sock);
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SDL_DestroyTexture(texture);
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SDL_DestroyRenderer(renderer);
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SDL_DestroyWindow(window);
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SDL_Quit();
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return EXIT_SUCCESS;
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}
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