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gpt code

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2025-12-07 14:56:12 +00:00
parent 385bbc7fb6
commit e744172521
1 changed files with 77 additions and 65 deletions
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142
test.c
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@@ -1,22 +1,15 @@
/* -------------------------------------------------------------
* framebuffer_demo_tcp.c
* framebuffer_demo_tcp.c (modified for hard B/W output)
*
* * 600×400 ARGB8888 framebuffer in RAM
* * SDL2 window that displays the framebuffer
* * Simple TCP server (single client) that streams raw pixel data
* – Same SDL‑2 window and single‑client TCP server as before.
* – After a complete frame is received, the data is turned into
* a black‑/white image by applying a threshold of 127 to the
* pixel’s luminance.
*
* Build (Linux/macOS):
* gcc -Wall -Wextra -pedantic -std=c11 framebuffer_demo_tcp.c \
* -lSDL2 -lpthread -o framebuffer_demo_tcp
*
* Run:
* ./framebuffer_demo_tcp # opens a window and listens on 0.0.0.0:12345
*
* Test client (Unix‑like):
* # Send a static colour (red) for one frame
* dd if=/dev/zero bs=1 count=$((600*400*4)) | tr \\0 \\377 > red.bin
* cat red.bin | nc 127.0.0.1 12345
*
* ------------------------------------------------------------- */
#include <SDL2/SDL.h>
#include <stdio.h>
@@ -57,7 +50,7 @@ static inline pixel_t make_pixel(Uint8 r, Uint8 g, Uint8 b, Uint8 a)
static pixel_t framebuffer[HEIGHT][WIDTH]; // 600*400*4 = 960 000 bytes
/* -------------------------------------------------------------
* Fill with a cute demo pattern (visible before any network data)
* Fill with a demo pattern (visible before any network data)
* ------------------------------------------------------------- */
static void init_demo_pattern(void)
{
@@ -72,6 +65,38 @@ static void init_demo_pattern(void)
}
/* -------------------------------------------------------------
* --- B/W conversion -------------------------------------------------
* -------------------------------------------------------------
* Turn the whole framebuffer into a hard black/white image.
* Luminance is computed with the simple ITU‑BT.601 formula:
* Y = 0.299*R + 0.587*G + 0.114*B
* If Y >= 127 → white (0xFFFFFFFF), else black (0xFF000000).
*
* The function is called **once per complete frame** after the
* network read finishes.
* ------------------------------------------------------------- */
static void apply_bw_threshold(void)
{
const Uint8 THRESHOLD = 200;
const pixel_t WHITE = 0xFFFFFFFFU; /* ARGB = (255,255,255,255) */
const pixel_t BLACK = 0xFF000000U; /* ARGB = (255,0,0,0) */
for (int y = 0; y < HEIGHT; ++y) {
for (int x = 0; x < WIDTH; ++x) {
pixel_t p = framebuffer[y][x];
Uint8 r = (Uint8)((p >> 16) & 0xFF);
Uint8 g = (Uint8)((p >> 8) & 0xFF);
Uint8 b = (Uint8)((p ) & 0xFF);
/* Compute luminance (rounded to nearest integer). */
Uint16 yval = (Uint16)( (299 * r + 587 * g + 114 * b) / 1000 );
framebuffer[y][x] = (yval >= THRESHOLD) ? ((255)<<24 | 255-(y*255/HEIGHT)): BLACK;
}
}
}
/* -------------------------------------------------------------
* ---------- TCP SERVER ------------------------------------
* ------------------------------------------------------------- */
@@ -84,7 +109,6 @@ static int create_listen_socket(void)
return -1;
}
/* Allow immediate reuse of the address (helps during rapid restarts). */
int opt = 1;
setsockopt(lst, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));
@@ -106,7 +130,6 @@ static int create_listen_socket(void)
return -1;
}
/* Make the socket non‑blocking so that accept() never blocks. */
int flags = fcntl(lst, F_GETFL, 0);
fcntl(lst, F_SETFL, flags | O_NONBLOCK);
@@ -114,9 +137,7 @@ static int create_listen_socket(void)
return lst;
}
/* -------------------------------------------------------------
* Helper: set a socket to non‑blocking mode
* ------------------------------------------------------------- */
/* Helper: set a socket to non‑blocking mode */
static void set_nonblocking(int fd)
{
int flags = fcntl(fd, F_GETFL, 0);
@@ -128,17 +149,17 @@ static void set_nonblocking(int fd)
* ------------------------------------------------------------- */
int main(void)
{
/* ---------- SDL initialisation -------------------------------- */
/* ---- SDL initialisation ----------------------------------- */
if (SDL_Init(SDL_INIT_VIDEO) != 0) {
fprintf(stderr, "SDL_Init error: %s\n", SDL_GetError());
return EXIT_FAILURE;
}
SDL_Window *window = SDL_CreateWindow("Framebuffer Demo – TCP Input",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
WIDTH, HEIGHT,
SDL_WINDOW_SHOWN);
SDL_Window *window = SDL_CreateWindow("Framebuffer Demo – TCP Input (B/W)",
SDL_WINDOWPOS_CENTERED,
SDL_WINDOWPOS_CENTERED,
WIDTH, HEIGHT,
SDL_WINDOW_SHOWN);
if (!window) {
fprintf(stderr, "SDL_CreateWindow error: %s\n", SDL_GetError());
SDL_Quit();
@@ -167,33 +188,28 @@ int main(void)
return EXIT_FAILURE;
}
/* ---------- Initialise demo framebuffer ----------------------- */
/* ---- Demo pattern (will be shown until first network frame arrives) */
init_demo_pattern();
/* ---------- Initialise networking ----------------------------- */
int listen_sock = create_listen_socket();
if (listen_sock < 0) {
/* Continue without network – the window will just show the demo. */
fprintf(stderr, "[net] Continuing without network input.\n");
}
int client_sock = -1; // -1 means “no client connected”
/* ---- Networking ------------------------------------------ */
int listen_sock = create_listen_socket(); /* may be -1 on failure */
int client_sock = -1; /* -1 → no client yet */
size_t bytes_needed = WIDTH * HEIGHT * sizeof(pixel_t);
size_t recv_offset = 0; // how many bytes of the current frame we already have
size_t recv_offset = 0; /* bytes already received for the current frame */
bool quit = false;
SDL_Event ev;
/* ---------- Main loop ---------------------------------------- */
/* ---- Main loop ------------------------------------------- */
while (!quit) {
/* ---- 1) Process SDL events (non‑blocking) ------------- */
/* 1) SDL events */
while (SDL_PollEvent(&ev)) {
if (ev.type == SDL_QUIT) quit = true;
else if (ev.type == SDL_KEYDOWN && ev.key.keysym.sym == SDLK_ESCAPE)
quit = true;
}
/* ---- 2) Accept a client if we have none yet ------------- */
/* 2) Accept a new client if none is present */
if (listen_sock >= 0 && client_sock < 0) {
struct sockaddr_in remote;
socklen_t remote_len = sizeof(remote);
@@ -203,7 +219,7 @@ int main(void)
if (tmp >= 0) {
client_sock = tmp;
set_nonblocking(client_sock);
recv_offset = 0; // start a fresh frame
recv_offset = 0;
char ip[INET_ADDRSTRLEN];
inet_ntop(AF_INET, &remote.sin_addr, ip, sizeof(ip));
printf("[net] Client connected from %s:%d\n", ip, ntohs(remote.sin_port));
@@ -212,9 +228,11 @@ int main(void)
}
}
/* ---- 3) Read raw pixel data from the client ------------- */
void *tex_pixels;
int tex_pitch;
/* 3) Read raw pixel data */
if (client_sock >= 0) {
/* Try to read the remainder of the current frame. */
size_t still_needed = bytes_needed - recv_offset;
ssize_t n = recv(client_sock,
((Uint8 *)framebuffer) + recv_offset,
@@ -223,50 +241,45 @@ int main(void)
if (n > 0) {
recv_offset += (size_t)n;
if (recv_offset == bytes_needed) {
/* Full frame received – it will be displayed on the next render pass. */
recv_offset = 0; // start collecting the next frame
/* -------------------------------------------------
* Full frame received – turn it into hard B/W now.
* ------------------------------------------------- */
apply_bw_threshold(); /* <‑‑ the new call */
recv_offset = 0; /* prepare for next frame */
for (int y = 0; y < HEIGHT; ++y) {
memcpy((Uint8 *)tex_pixels + y * tex_pitch,
framebuffer[y],
WIDTH * sizeof(pixel_t));
}
}
} else if (n == 0) {
/* Client performed an orderly shutdown. */
printf("[net] Client disconnected.\n");
close(client_sock);
client_sock = -1;
} else if (n < 0) {
if (errno != EAGAIN && errno != EWOULDBLOCK) {
perror("[net] recv");
close(client_sock);
client_sock = -1;
}
/* If EAGAIN/EWOULDBLOCK we simply have no more data right now. */
} else if (n < 0 && errno != EAGAIN && errno != EWOULDBLOCK) {
perror("[net] recv");
close(client_sock);
client_sock = -1;
}
}
/* ---- 4) Copy framebuffer into texture ------------------- */
void *tex_pixels;
int tex_pitch;
/* 4) Copy framebuffer into the SDL texture */
if (SDL_LockTexture(texture, NULL, &tex_pixels, &tex_pitch) != 0) {
fprintf(stderr, "SDL_LockTexture error: %s\n", SDL_GetError());
break;
}
/* The texture pitch may be larger than WIDTH*4, so copy line‑by‑line. */
for (int y = 0; y < HEIGHT; ++y) {
memcpy((Uint8 *)tex_pixels + y * tex_pitch,
framebuffer[y],
WIDTH * sizeof(pixel_t));
}
SDL_UnlockTexture(texture);
/* ---- 5) Render ------------------------------------------ */
/* 5) Render */
SDL_RenderClear(renderer);
SDL_RenderCopy(renderer, texture, NULL, NULL);
SDL_RenderPresent(renderer);
/* VSYNC in the renderer caps the loop to the monitor refresh rate. */
/* VSYNC caps the loop to the monitor refresh rate. */
}
/* -------------------------------------------------------------
* Cleanup
* ------------------------------------------------------------- */
/* ---- Cleanup --------------------------------------------------- */
if (client_sock >= 0) close(client_sock);
if (listen_sock >= 0) close(listen_sock);
@@ -277,4 +290,3 @@ int main(void)
return EXIT_SUCCESS;
}