implement area clearing on the ESP32-S3

examples/fb_mode_test/main/main.c

@@ -23,6 +23,7 @@
 
 #include <epdiy.h>
 
+#include "epd_display.h"
 #include "sdkconfig.h"
 
 #define WAVEFORM EPD_BUILTIN_WAVEFORM
@@ -55,6 +56,16 @@ void clear() {
     memset(framebuffer, 0xFF, fb_size);
 }
 
+/**
+ * Clear an example area on the screen to white, does not reset the framebuffer.
+ */
+void clear_area(EpdRect clear_area) {
+    epd_poweron();
+    epd_clear_area(clear_area);
+    epd_poweroff();
+    memset(framebuffer, 0xFF, fb_size);
+}
+
 /**
  * Draw triangles at varying alignments into the framebuffer in 8ppB mode.
  * start_line, start_column specify the start position.
@@ -197,7 +208,16 @@ void app_main() {
 
     test_2ppB();
 
+    // Clear at different positions
+    EpdRect area = { .x = 100, .y = epd_height() - 200, .width = 80, .height = 100 };
+    clear_area(area);
+    area.width += 1;
+    area.x += 100;
+    clear_area(area);
+    area.x += 101;
+    clear_area(area);
+
     printf("going to sleep...\n");
     epd_deinit();
     esp_deep_sleep_start();
-}
+}

src/output_common/render_context.c

@@ -1,5 +1,6 @@
 #include "render_context.h"
 
+#include <string.h>
 #include "esp_log.h"
 
 #include "../epdiy.h"
@@ -87,3 +88,19 @@ void IRAM_ATTR prepare_context_for_next_frame(RenderContext_t* ctx) {
     ctx->lines_prepared = 0;
     ctx->lines_consumed = 0;
 }
+
+void epd_populate_line_mask(uint8_t* line_mask, const uint8_t* dirty_columns, int mask_len) {
+    if (dirty_columns == NULL) {
+        memset(line_mask, 0xFF, mask_len);
+    } else {
+        int pixels = mask_len * 4;
+        for (int c = 0; c < pixels / 2; c += 2) {
+            uint8_t mask = 0;
+            mask |= (dirty_columns[c + 1] & 0xF0) != 0 ? 0xC0 : 0x00;
+            mask |= (dirty_columns[c + 1] & 0x0F) != 0 ? 0x30 : 0x00;
+            mask |= (dirty_columns[c] & 0xF0) != 0 ? 0x0C : 0x00;
+            mask |= (dirty_columns[c] & 0x0F) != 0 ? 0x03 : 0x00;
+            line_mask[c / 2] = mask;
+        }
+    }
+}

src/output_common/render_context.h

@@ -74,6 +74,9 @@ typedef struct {
 
     /// track line skipping when working in old i2s mode
     int skipping;
+
+    /// line buffer when using epd_push_pixels
+    uint8_t* static_line_buffer;
 } RenderContext_t;
 
 /**
@@ -95,3 +98,13 @@ void get_buffer_params(
  * (Reset counters, etc)
  */
 void prepare_context_for_next_frame(RenderContext_t* ctx);
+
+/**
+ * Populate an output line mask from line dirtyness with two bits per pixel.
+ * If the dirtyness data is NULL, set the mask to neutral.
+ *
+ * don't inline for to ensure availability in tests.
+ */
+void __attribute__((noinline)) epd_populate_line_mask(
+    uint8_t* line_mask, const uint8_t* dirty_columns, int mask_len
+);

src/output_lcd/render_lcd.c

@@ -17,20 +17,8 @@
 #include "lcd_driver.h"
 #include "render_lcd.h"
 
-static bool IRAM_ATTR fill_line_noop(RenderContext_t* ctx, uint8_t* line) {
-    memset(line, 0x00, ctx->display_width / 4);
-    return false;
-}
-
-static bool IRAM_ATTR fill_line_white(RenderContext_t* ctx, uint8_t* line) {
-    memset(line, CLEAR_BYTE, ctx->display_width / 4);
-    return false;
-}
-
-static bool IRAM_ATTR fill_line_black(RenderContext_t* ctx, uint8_t* line) {
-    memset(line, DARK_BYTE, ctx->display_width / 4);
-    return false;
-}
+// declare vector optimized line mask application.
+void epd_apply_line_mask_VE(uint8_t* line, const uint8_t* mask, int mask_len);
 
 __attribute__((optimize("O3"))) static bool IRAM_ATTR
 retrieve_line_isr(RenderContext_t* ctx, uint8_t* buf) {
@@ -97,20 +85,75 @@ void lcd_do_update(RenderContext_t* ctx) {
     epd_set_mode(0);
 }
 
+__attribute__((optimize("O3"))) static bool IRAM_ATTR
+push_pixels_isr(RenderContext_t* ctx, uint8_t* buf) {
+    // Output no-op outside of drawn area
+    if (ctx->lines_consumed < ctx->area.y) {
+        memset(buf, 0, ctx->display_width / 4);
+    } else if (ctx->lines_consumed >= ctx->area.y + ctx->area.height) {
+        memset(buf, 0, ctx->display_width / 4);
+    } else {
+        memcpy(buf, ctx->static_line_buffer, ctx->display_width / 4);
+    }
+    ctx->lines_consumed += 1;
+    return pdFALSE;
+}
+
+/**
+ * Populate the line mask for use in epd_push_pixels.
+ */
+static void push_pixels_populate_line(RenderContext_t* ctx, int color) {
+    // Select fill pattern by draw color
+    int fill_byte = 0;
+    switch (color) {
+        case 0:
+            fill_byte = DARK_BYTE;
+            break;
+        case 1:
+            fill_byte = CLEAR_BYTE;
+            break;
+        default:
+            fill_byte = 0x00;
+    }
+
+    // Compute a line mask based on the drawn area
+    uint8_t* dirtyness = malloc(ctx->display_width / 2);
+    assert(dirtyness != NULL);
+
+    memset(dirtyness, 0, ctx->display_width / 2);
+
+    for (int i = 0; i < ctx->display_width; i++) {
+        if ((i >= ctx->area.x) && (i < ctx->area.x + ctx->area.width)) {
+            dirtyness[i / 2] |= i % 2 ? 0xF0 : 0x0F;
+        }
+    }
+    epd_populate_line_mask(ctx->line_mask, dirtyness, ctx->display_width / 4);
+
+    // mask the line pattern with the populated mask
+    memset(ctx->static_line_buffer, fill_byte, ctx->display_width / 4);
+    epd_apply_line_mask(ctx->static_line_buffer, ctx->line_mask, ctx->display_width / 4);
+
+    free(dirtyness);
+}
+
 void epd_push_pixels_lcd(RenderContext_t* ctx, short time, int color) {
-    epd_set_mode(1);
     ctx->current_frame = 0;
+    ctx->lines_total = ctx->display_height;
+    ctx->lines_consumed = 0;
+    ctx->static_line_buffer = malloc(ctx->display_width / 4);
+    assert(ctx->static_line_buffer != NULL);
+
+    push_pixels_populate_line(ctx, color);
     epd_lcd_frame_done_cb((frame_done_func_t)handle_lcd_frame_done, ctx);
-    if (color == 0) {
-        epd_lcd_line_source_cb((line_cb_func_t)&fill_line_black, ctx);
-    } else if (color == 1) {
-        epd_lcd_line_source_cb((line_cb_func_t)&fill_line_white, ctx);
-    } else {
-        epd_lcd_line_source_cb((line_cb_func_t)&fill_line_noop, ctx);
-    }
+    epd_lcd_line_source_cb((line_cb_func_t)&push_pixels_isr, ctx);
+
+    epd_set_mode(1);
     epd_lcd_start_frame();
     xSemaphoreTake(ctx->frame_done, portMAX_DELAY);
     epd_set_mode(0);
+
+    free(ctx->static_line_buffer);
+    ctx->static_line_buffer = NULL;
 }
 
 #define int_min(a, b) (((a) < (b)) ? (a) : (b))
@@ -194,7 +237,6 @@ lcd_calculate_frame(RenderContext_t* ctx, int thread_id) {
         ctx->lut_lookup_func(lp, buf, ctx->conversion_lut, ctx->display_width);
 
         // apply the line mask
-        void epd_apply_line_mask_VE(uint8_t * line, const uint8_t* mask, int mask_len);
         epd_apply_line_mask_VE(buf, ctx->line_mask, ctx->display_width / 4);
 
         lq_commit(lq);

src/render.c

@@ -88,29 +88,6 @@ static inline int rounded_display_height() {
     return (((epd_height() + 7) / 8) * 8);
 }
 
-/**
- * Populate an output line mask from line dirtyness with one nibble per pixel.
- * If the dirtyness data is NULL, set the mask to neutral.
- *
- * don't inline for to ensure availability in tests.
- */
-void __attribute__((noinline))
-_epd_populate_line_mask(uint8_t* line_mask, const uint8_t* dirty_columns, int mask_len) {
-    if (dirty_columns == NULL) {
-        memset(line_mask, 0xFF, mask_len);
-    } else {
-        int pixels = mask_len * 4;
-        for (int c = 0; c < pixels / 2; c += 2) {
-            uint8_t mask = 0;
-            mask |= (dirty_columns[c + 1] & 0xF0) != 0 ? 0xC0 : 0x00;
-            mask |= (dirty_columns[c + 1] & 0x0F) != 0 ? 0x30 : 0x00;
-            mask |= (dirty_columns[c] & 0xF0) != 0 ? 0x0C : 0x00;
-            mask |= (dirty_columns[c] & 0x0F) != 0 ? 0x03 : 0x00;
-            line_mask[c / 2] = mask;
-        }
-    }
-}
-
 // FIXME: fix misleading naming:
 //  area -> buffer dimensions
 //  crop -> area taken out of buffer
@@ -198,7 +175,7 @@ enum EpdDrawError IRAM_ATTR epd_draw_base(
         render_context.phase_times = waveform_phases->phase_times;
     }
 
-    _epd_populate_line_mask(
+    epd_populate_line_mask(
         render_context.line_mask, drawn_columns, render_context.display_width / 4
     );
 
@@ -294,6 +271,7 @@ void epd_renderer_init(enum EpdInitOptions options) {
         abort();
     }
     render_context.conversion_lut_size = lut_size;
+    render_context.static_line_buffer = NULL;
 
     render_context.frame_done = xSemaphoreCreateBinary();
 

test/test_line_mask.c

@@ -3,14 +3,14 @@
 #include <sys/types.h>
 #include <unity.h>
 
-void _epd_populate_line_mask(uint8_t* line_mask, const uint8_t* dirty_columns, int mask_len);
+void epd_populate_line_mask(uint8_t* line_mask, const uint8_t* dirty_columns, int mask_len);
 
 const uint8_t col_dirtyness_example[8] = { 0x00, 0x0F, 0x00, 0x11, 0xFF, 0xFF, 0x00, 0x80 };
 
 TEST_CASE("mask populated correctly", "[epdiy,unit]") {
     const uint8_t expected_mask[8] = { 0x30, 0xF0, 0xFF, 0xC0, 0x00, 0x00, 0x00, 0x00 };
     uint8_t mask[8] = { 0 };
-    _epd_populate_line_mask(mask, col_dirtyness_example, 4);
+    epd_populate_line_mask(mask, col_dirtyness_example, 4);
 
     TEST_ASSERT_EQUAL_UINT8_ARRAY(expected_mask, mask, 8);
 }
@@ -19,7 +19,7 @@ TEST_CASE("neutral mask with null dirtyness", "[epdiy,unit]") {
     const uint8_t expected_mask[8] = { 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, 0x00, 0x00 };
     uint8_t mask[8] = { 0 };
 
-    _epd_populate_line_mask(mask, NULL, 4);
+    epd_populate_line_mask(mask, NULL, 4);
 
     TEST_ASSERT_EQUAL_UINT8_ARRAY(expected_mask, mask, 8);
 }