Merge pull request adafruit#9479 from pypewpew/bug-6675

displayio.Bitmap is now byte-aligned for depth < 8

Author: tannewt

shared-module/displayio/Bitmap.c

@@ -49,7 +49,7 @@ void common_hal_displayio_bitmap_construct_from_buffer(displayio_bitmap_t *self,
     self->x_shift = 0; // Used to divide the index by the number of pixels per word. Its used in a
                        // shift which effectively divides by 2 ** x_shift.
     uint32_t power_of_two = 1;
-    while (power_of_two < ALIGN_BITS / bits_per_value) {
+    while (power_of_two < 8 / bits_per_value) {
         self->x_shift++;
         power_of_two <<= 1;
     }
@@ -90,13 +90,14 @@ uint32_t common_hal_displayio_bitmap_get_pixel(displayio_bitmap_t *self, int16_t
         return 0;
     }
     int32_t row_start = y * self->stride;
-    uint32_t bytes_per_value = self->bits_per_value / 8;
+    uint32_t *row = self->data + row_start;
+    uint8_t bytes_per_value = self->bits_per_value / 8;
+    uint8_t values_per_byte = 8 / self->bits_per_value;
     if (bytes_per_value < 1) {
-        uint32_t word = self->data[row_start + (x >> self->x_shift)];
-
-        return (word >> (sizeof(uint32_t) * 8 - ((x & self->x_mask) + 1) * self->bits_per_value)) & self->bitmask;
+        uint8_t bits = ((uint8_t *)row)[x >> self->x_shift];
+        uint8_t bit_position = (values_per_byte - (x & self->x_mask) - 1) * self->bits_per_value;
+        return (bits >> bit_position) & self->bitmask;
     } else {
-        uint32_t *row = self->data + row_start;
         if (bytes_per_value == 1) {
             return ((uint8_t *)row)[x];
         } else if (bytes_per_value == 2) {
@@ -134,16 +135,16 @@ void displayio_bitmap_write_pixel(displayio_bitmap_t *self, int16_t x, int16_t y
 
     // Update one pixel of data
     int32_t row_start = y * self->stride;
-    uint32_t bytes_per_value = self->bits_per_value / 8;
+    uint32_t *row = self->data + row_start;
+    uint8_t bytes_per_value = self->bits_per_value / 8;
+    uint8_t values_per_byte = 8 / self->bits_per_value;
     if (bytes_per_value < 1) {
-        uint32_t bit_position = (sizeof(uint32_t) * 8 - ((x & self->x_mask) + 1) * self->bits_per_value);
-        uint32_t index = row_start + (x >> self->x_shift);
-        uint32_t word = self->data[index];
-        word &= ~(self->bitmask << bit_position);
-        word |= (value & self->bitmask) << bit_position;
-        self->data[index] = word;
+        uint8_t bits = ((uint8_t *)row)[x >> self->x_shift];
+        uint8_t bit_position = (values_per_byte - (x & self->x_mask) - 1) * self->bits_per_value;
+        bits &= ~(self->bitmask << bit_position);
+        bits |= (value & self->bitmask) << bit_position;
+        ((uint8_t *)row)[x >> self->x_shift] = bits;
     } else {
-        uint32_t *row = self->data + row_start;
         if (bytes_per_value == 1) {
             ((uint8_t *)row)[x] = value;
         } else if (bytes_per_value == 2) {

tools/gen_display_resources.py

@@ -122,22 +122,22 @@ def _load_row(self, y, row):
     c_file.write(
         """\
 const uint32_t blinka_bitmap_data[32] = {
-    0x00000011, 0x11000000,
-    0x00000111, 0x53100000,
-    0x00000111, 0x56110000,
-    0x00000111, 0x11140000,
-    0x00000111, 0x20002000,
-    0x00000011, 0x13000000,
-    0x00000001, 0x11200000,
-    0x00000000, 0x11330000,
-    0x00000000, 0x01122000,
-    0x00001111, 0x44133000,
-    0x00032323, 0x24112200,
-    0x00111114, 0x44113300,
-    0x00323232, 0x34112200,
-    0x11111144, 0x44443300,
-    0x11111111, 0x11144401,
-    0x23232323, 0x21111110
+    0x11000000, 0x00000011,
+    0x11010000, 0x00001053,
+    0x11010000, 0x00001156,
+    0x11010000, 0x00001411,
+    0x11010000, 0x00200020,
+    0x11000000, 0x00000013,
+    0x01000000, 0x00002011,
+    0x00000000, 0x00003311,
+    0x00000000, 0x00201201,
+    0x11110000, 0x00301344,
+    0x23230300, 0x00221124,
+    0x14111100, 0x00331144,
+    0x32323200, 0x00221134,
+    0x44111111, 0x00334444,
+    0x11111111, 0x01441411,
+    0x23232323, 0x10111121
 };
 """
     )
@@ -146,18 +146,18 @@ def _load_row(self, y, row):
     c_file.write(
         """\
 const uint32_t blinka_bitmap_data[28] = {
-    0x00000111, 0x00000000,
-    0x00001153, 0x10000000,
-    0x00001156, 0x11000000,
-    0x00001111, 0x14000000,
-    0x00000112, 0x00200000,
-    0x00000011, 0x30000000,
-    0x00000011, 0x20000000,
-    0x00011144, 0x13000000,
-    0x00232324, 0x12000000,
-    0x01111444, 0x13000000,
-    0x32323234, 0x12010000,
-    0x11111144, 0x44100000
+    0x11010000, 0x00000000,
+    0x53110000, 0x00000010,
+    0x56110000, 0x00000011,
+    0x11110000, 0x00000014,
+    0x12010000, 0x00002000,
+    0x11000000, 0x00000030,
+    0x11000000, 0x00000020,
+    0x44110100, 0x00000013,
+    0x24232300, 0x00000012,
+    0x44141101, 0x00000013,
+    0x34323232, 0x00000112,
+    0x44111111, 0x00001044
 };
 """
     )
@@ -171,9 +171,9 @@ def _load_row(self, y, row):
     .data = (uint32_t*) blinka_bitmap_data,
     .stride = 2,
     .bits_per_value = 4,
-    .x_shift = 3,
-    .x_mask = 0x7,
-    .bitmask = 0xf,
+    .x_shift = 1,
+    .x_mask = 0x01,
+    .bitmask = 0x0f,
     .read_only = true
 }};
 
@@ -328,7 +328,7 @@ def _load_row(self, y, row):
     )
 )
 
-for i, word in enumerate(struct.iter_unpack(">I", b)):
+for i, word in enumerate(struct.iter_unpack("<I", b)):
     c_file.write("0x{:08x}, ".format(word[0]))
     if (i + 1) % (bytes_per_row // 4) == 0:
         c_file.write("\n")
@@ -348,9 +348,9 @@ def _load_row(self, y, row):
     .data = (uint32_t*) font_bitmap_data,
     .stride = {},
     .bits_per_value = 1,
-    .x_shift = 5,
-    .x_mask = 0x1f,
-    .bitmask = 0x1,
+    .x_shift = 3,
+    .x_mask = 0x07,
+    .bitmask = 0x01,
     .read_only = true
 }};
 """.format(