From 4e07116103e2fa09dd451a1399129cbfa457440c Mon Sep 17 00:00:00 2001
From: Alejandro Laguna <alejandro.laguna@proton.me>
Date: Thu, 30 Jul 2026 10:38:58 +0200
Subject: [PATCH] feat: multithreading using pthread

---
 Makefile   |  2 +-
 src/main.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++----
 2 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/Makefile b/Makefile
index debcc6bbf23f5a4288d91f6bb3142fbb2218c002..d06c2f05055ee8faec77678be522e21b82308dcf 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 CC = gcc
 CFLAGS = -Wall -Wextra -Werror -g3 -I include/
-LIBFLAGS = -lm -lSDL3
+LIBFLAGS = -lm -lSDL3 -pthread
  
 SRC = src/main.c src/draw.c src/math.c
 OBJ = $(SRC:.c=.o)
diff --git a/src/main.c b/src/main.c
index 1b68d61e92b94f56ce73cbf8ca6997302e802562..1538a19f158c49febeb99b8eaa9f4f3497739267 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,7 +7,7 @@
 #include <SDL3/SDL_render.h>
 #include <SDL3/SDL_surface.h>
 #include <SDL3/SDL_video.h>
-#include <math.h>
+#include <pthread.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -15,7 +15,7 @@
 extern int points[WINDOW_WIDTH * WINDOW_HEIGHT];
 
 state_t* init() {
-    state_t *state = malloc(sizeof(state_t));
+    state_t* state = malloc(sizeof(state_t));
     if (!SDL_Init(SDL_INIT_VIDEO | SDL_INIT_EVENTS)) {
         fprintf(stderr, "SDL_Init failed: %s\n", SDL_GetError());
         return NULL;
@@ -51,8 +51,58 @@ state_t* init() {
     return state;
 }
 
+typedef struct {
+    position_t* pos;
+    int start_row;
+    int end_row;
+    int max_iter;
+} thread_data_t;
+
+void* calculate_points_thread(void* arg) {
+    thread_data_t* data = (thread_data_t*)arg;
+    position_t* pos = data->pos;
+    int max_iter = data->max_iter;
+
+    for (int py = data->start_row; py < data->end_row; py++) {
+        for (int px = 0; px < WINDOW_WIDTH; px++) {
+            double cr = pos->x_min + (pos->x_max - pos->x_min) * px / (WINDOW_WIDTH - 1);
+            double ci = pos->y_min + (pos->y_max - pos->y_min) * py / (WINDOW_HEIGHT - 1);
+            points[py * WINDOW_WIDTH + px] = mandelbrot_iterations(cr, ci, max_iter);
+        }
+    }
+    return NULL;
+}
+
+void calculate_points_pthread(position_t* pos) {
+    int max_iter = 100;
+    int num_threads = 4;
+
+    pthread_t threads[num_threads];
+    thread_data_t thread_data[num_threads];
+
+    int rows_per_thread = WINDOW_HEIGHT / num_threads;
+    int remaining_rows = WINDOW_HEIGHT % num_threads;
+
+    for (int t = 0; t < num_threads; t++) {
+        thread_data[t].pos = pos;
+        thread_data[t].start_row = t * rows_per_thread;
+        thread_data[t].end_row = (t + 1) * rows_per_thread;
+        thread_data[t].max_iter = max_iter;
+
+        if (t == num_threads - 1) {
+            thread_data[t].end_row += remaining_rows;
+        }
+
+        pthread_create(&threads[t], NULL, calculate_points_thread, &thread_data[t]);
+    }
+
+    for (int t = 0; t < num_threads; t++) {
+        pthread_join(threads[t], NULL);
+    }
+}
+
 int main(void) {
-    state_t *state = init();
+    state_t* state = init();
     if (state == NULL) {
         return -1;
     }
@@ -156,7 +206,8 @@ int main(void) {
             }
         }
         if (pos_updated) {
-            calculate_points(&position);
+            // calculate_points(&position);
+            calculate_points_pthread(&position);
             pos_updated = false;
         }
         draw_points(state->surface);