dangernoodle-io / breadboard / 26003381796

100%

push

github

perf(bb_display_st77xx): replace 16KB transient malloc with tiled blit (#259)

Heap audit P3-D (backlog B1-208): bb_display_st77xx_blit previously
allocated up to pixel_count * sizeof(uint16_t) = 16,384 B contiguous
from the default heap on every large blit (max 8192 px). On ESP32-S3
boards without PSRAM (bitaxe-650, tdongle-s3) this transient competes
with mbedtls handshakes and other large allocs.

Replace with the same bounce-buffer tiled approach already used by the
ILI9341 backend: a static uint16_t bounce[512] buffer (1 KB, in
.bss/.data, DMA-capable) tiles the blit row-by-row. Pixel order is
preserved exactly — tile boundaries fall on whole rows. No API change.

Visual regression risk is low: the tile loop submits identical pixel
data in the same order as the previous single-pass path; the only
observable difference is the number of esp_lcd_panel_draw_bitmap calls,
which the panel driver already handles transparently.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

960 of 960 branches covered (100.0%)

Branch coverage included in aggregate %.

1722 of 1722 relevant lines covered (100.0%)

1016.42 hits per line