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display/low_level_display_st7789.cpp

@@ -1,15 +1,19 @@
 #include "low_level_display_st7789.h"
 #include <stdio.h>
+#include <stdlib.h>
 
 // Note: This is a placeholder implementation
 // You'll need to add the actual ST7789 driver code to lib/st7789/
 
 LowLevelDisplayST7789::LowLevelDisplayST7789(const st7789_config* cfg, int w, int h)
-    : config(cfg), width(w), height(h), initialized(false) {
+    : config(cfg), width(w), height(h), initialized(false), rgb_buffer(nullptr) {
 }
 
 LowLevelDisplayST7789::~LowLevelDisplayST7789() {
-    // Cleanup if needed
+    if (rgb_buffer) {
+        free(rgb_buffer);
+        rgb_buffer = nullptr;
+    }
 }
 
 bool LowLevelDisplayST7789::init() {
@@ -19,6 +23,15 @@ bool LowLevelDisplayST7789::init() {
     
     // TODO: Implement ST7789 initialization
     // st7789_init(config, width, height);
+    // 
+    // TODO: Allocate RGB565 buffer once (reused for all draw operations)
+    // size_t buffer_size = width * height * sizeof(uint16_t);
+    // rgb_buffer = (uint16_t *)malloc(buffer_size);
+    // if (!rgb_buffer) {
+    //     printf("Error: Failed to allocate %zu bytes for RGB buffer\n", buffer_size);
+    //     return false;
+    // }
+    
     printf("ST7789 display initialized: %dx%d (stub)\n", width, height);
     initialized = true;
     return false;  // Return false until actual driver is implemented
@@ -36,6 +49,18 @@ void LowLevelDisplayST7789::draw_pixel(int x, int y, bool white) {
 
 void LowLevelDisplayST7789::draw_buffer(const uint8_t* bit_buffer) {
     // TODO: Implement - convert 1-bit to RGB565 and write
+    // IMPORTANT: Use the persistent rgb_buffer member, NOT malloc/free!
+    // Example:
+    //   if (!bit_buffer || !rgb_buffer) return;
+    //   for (int y = 0; y < height; y++) {
+    //       for (int x = 0; x < width; x++) {
+    //           int byte_index = (y * width + x) / 8;
+    //           int bit_index = 7 - (x % 8);
+    //           bool pixel_white = (bit_buffer[byte_index] >> bit_index) & 0x01;
+    //           rgb_buffer[y * width + x] = pixel_white ? COLOR_WHITE : COLOR_BLACK;
+    //       }
+    //   }
+    //   st7789_write(rgb_buffer, width * height);
     (void)bit_buffer;
 }
 

display/low_level_display_st7789.h

@@ -20,6 +20,7 @@ private:
     int width;
     int height;
     bool initialized;
+    uint16_t* rgb_buffer;  // Persistent buffer for 1-bit to RGB565 conversion
     
 public:
     LowLevelDisplayST7789(const st7789_config* cfg, int w, int h);

display/low_level_display_st7796.cpp

@@ -7,11 +7,14 @@
 #define COLOR_WHITE   0xFFFF
 
 LowLevelDisplayST7796::LowLevelDisplayST7796(const st7796_config* cfg, int w, int h)
-    : config(cfg), width(w), height(h), initialized(false) {
+    : config(cfg), width(w), height(h), initialized(false), rgb_buffer(nullptr) {
 }
 
 LowLevelDisplayST7796::~LowLevelDisplayST7796() {
-    // Cleanup if needed
+    if (rgb_buffer) {
+        free(rgb_buffer);
+        rgb_buffer = nullptr;
+    }
 }
 
 bool LowLevelDisplayST7796::init() {
@@ -20,8 +23,17 @@ bool LowLevelDisplayST7796::init() {
     }
     
     st7796_init(config, width, height);
+    
+    // Allocate RGB565 buffer once (reused for all draw operations)
+    size_t buffer_size = width * height * sizeof(uint16_t);
+    rgb_buffer = (uint16_t *)malloc(buffer_size);
+    if (!rgb_buffer) {
+        printf("Error: Failed to allocate %zu bytes for RGB buffer\n", buffer_size);
+        return false;
+    }
+    printf("ST7796 display initialized: %dx%d (RGB buffer: %zu bytes)\n", width, height, buffer_size);
+    
     initialized = true;
-    printf("ST7796 display initialized: %dx%d\n", width, height);
     return true;
 }
 
@@ -34,16 +46,9 @@ void LowLevelDisplayST7796::draw_pixel(int x, int y, bool white) {
 }
 
 void LowLevelDisplayST7796::draw_buffer(const uint8_t* bit_buffer) {
-    if (!bit_buffer) return;
+    if (!bit_buffer || !rgb_buffer) return;
     
-    // Allocate RGB565 buffer for entire screen
-    uint16_t *rgb_buffer = (uint16_t *)malloc(width * height * sizeof(uint16_t));
-    if (!rgb_buffer) {
-        printf("Error: Failed to allocate RGB buffer\n");
-        return;
-    }
-    
-    // Convert 1-bit buffer to RGB565
+    // Convert 1-bit buffer to RGB565 using persistent buffer
     for (int y = 0; y < height; y++) {
         for (int x = 0; x < width; x++) {
             int byte_index = (y * width + x) / 8;
@@ -56,8 +61,6 @@ void LowLevelDisplayST7796::draw_buffer(const uint8_t* bit_buffer) {
     // Draw entire buffer at once
     st7796_set_cursor(0, 0);
     st7796_write(rgb_buffer, width * height);
-    
-    free(rgb_buffer);
 }
 
 void LowLevelDisplayST7796::refresh() {

display/low_level_display_st7796.h

@@ -10,6 +10,7 @@ private:
     int width;
     int height;
     bool initialized;
+    uint16_t* rgb_buffer;  // Persistent buffer for 1-bit to RGB565 conversion
     
 public:
     LowLevelDisplayST7796(const st7796_config* cfg, int w, int h);