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RGB565 byteswapped format #1

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4b03c99
extmod/modframebuf.c: Add byte-swapped RGB565 format.
corranwebster Nov 14, 2025
eb96c71
tests/extmod/framebuf16_bs.py
corranwebster Nov 14, 2025
19ba0e0
extmod/modframebuf.c: Add RGB565_BS to valid format cases.
corranwebster Nov 17, 2025
845dcad
tests/extmod/framebuf16_bs.py: Correct buffer type.
corranwebster Nov 17, 2025
86ce41d
run-tests.py: Skip framebuf16_bs tests on platforms without slicing.
corranwebster Nov 17, 2025
e197cd4
docs/framebuf.rst: Add documentation for new format.
corranwebster Nov 17, 2025
91cfa99
examples/natmod/framebuf.c: Add RGB565_BS to example native module.
corranwebster Nov 17, 2025
7b66bd1
extmod/modframebuf.c: Reduce codesize.
corranwebster Nov 17, 2025
700085e
extmod/modframbeuf.c: Completely remove byteswapped fill rect.
corranwebster Nov 17, 2025
1948f36
extmod/modframebuf.c: Make RGB565 endianness explicit.
corranwebster Nov 17, 2025
f1f616d
extmod/modframebuf.c: Fix code style
corranwebster Nov 17, 2025
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15 changes: 14 additions & 1 deletion docs/library/framebuf.rst
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Original file line number Diff line number Diff line change
Expand Up @@ -192,7 +192,20 @@ Constants

.. data:: framebuf.RGB565

Red Green Blue (16-bit, 5+6+5) color format
Red Green Blue (16-bit, 5+6+5, native) color format in native byte-order.

.. data:: framebuf.RGB565_LE

Red Green Blue (16-bit, 5+6+5, little-endian) color format in little-endian
byte order. This defines a 16-bit format where the bytes are stored in
little-endian order. If the system is little-endian, this is the same as
``RGB565``.

.. data:: framebuf.RGB565_BE

Red Green Blue (16-bit, 5+6+5, big-endian) color format in big-endian byte
order. This defines a 16-bit format where the bytes are stored in
big-endian order. If the system is big-endian, this is the same as ``RGB565``.

.. data:: framebuf.GS2_HMSB

Expand Down
7 changes: 7 additions & 0 deletions examples/natmod/framebuf/framebuf.c
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Expand Up @@ -44,6 +44,13 @@ mp_obj_t mpy_init(mp_obj_fun_bc_t *self, size_t n_args, size_t n_kw, mp_obj_t *a
mp_store_global(MP_QSTR_MVLSB, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_MVLSB));
mp_store_global(MP_QSTR_MONO_VLSB, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_MVLSB));
mp_store_global(MP_QSTR_RGB565, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_RGB565));
#if MP_ENDIANNESS_LITTLE
mp_store_global(MP_QSTR_RGB565_LE, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_RGB565));
mp_store_global(MP_QSTR_RGB565_BE, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_RGB565_BS));
#else
mp_store_global(MP_QSTR_RGB565_BE, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_RGB565));
mp_store_global(MP_QSTR_RGB565_LE, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_RGB565_BS));
#endif
mp_store_global(MP_QSTR_GS2_HMSB, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_GS2_HMSB));
mp_store_global(MP_QSTR_GS4_HMSB, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_GS4_HMSB));
mp_store_global(MP_QSTR_GS8, MP_OBJ_NEW_SMALL_INT(FRAMEBUF_GS8));
Expand Down
42 changes: 34 additions & 8 deletions extmod/modframebuf.c
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Expand Up @@ -57,13 +57,14 @@ typedef struct _mp_framebuf_p_t {
} mp_framebuf_p_t;

// constants for formats
#define FRAMEBUF_MVLSB (0)
#define FRAMEBUF_RGB565 (1)
#define FRAMEBUF_GS2_HMSB (5)
#define FRAMEBUF_GS4_HMSB (2)
#define FRAMEBUF_GS8 (6)
#define FRAMEBUF_MHLSB (3)
#define FRAMEBUF_MHMSB (4)
#define FRAMEBUF_MVLSB (0)
#define FRAMEBUF_RGB565 (1)
#define FRAMEBUF_RGB565_BS (7)
#define FRAMEBUF_GS2_HMSB (5)
#define FRAMEBUF_GS4_HMSB (2)
#define FRAMEBUF_GS8 (6)
#define FRAMEBUF_MHLSB (3)
#define FRAMEBUF_MHMSB (4)

// Functions for MHLSB and MHMSB

Expand Down Expand Up @@ -117,7 +118,10 @@ static void mvlsb_fill_rect(const mp_obj_framebuf_t *fb, unsigned int x, unsigne
}
}

// Functions for RGB565 format
// Functions for RGB565 and RGB565_BS format
//
// Internally we use 'native' and 'byte-swapped' formats, and then expose those as big- or little-
// endian to Python as appropriate.

static void rgb565_setpixel(const mp_obj_framebuf_t *fb, unsigned int x, unsigned int y, uint32_t col) {
((uint16_t *)fb->buf)[x + y * fb->stride] = col;
Expand All @@ -127,7 +131,20 @@ static uint32_t rgb565_getpixel(const mp_obj_framebuf_t *fb, unsigned int x, uns
return ((uint16_t *)fb->buf)[x + y * fb->stride];
}

static void rgb565_bs_setpixel(const mp_obj_framebuf_t *fb, unsigned int x, unsigned int y, uint32_t col) {
col = __builtin_bswap16(col);
((uint16_t *)fb->buf)[x + y * fb->stride] = col;
}

static uint32_t rgb565_bs_getpixel(const mp_obj_framebuf_t *fb, unsigned int x, unsigned int y) {
uint32_t col = ((uint16_t *)fb->buf)[x + y * fb->stride];
return __builtin_bswap16(col);
}

static void rgb565_fill_rect(const mp_obj_framebuf_t *fb, unsigned int x, unsigned int y, unsigned int w, unsigned int h, uint32_t col) {
if (fb->format == FRAMEBUF_RGB565_BS) {
col = __builtin_bswap16(col);
}
uint16_t *b = &((uint16_t *)fb->buf)[x + y * fb->stride];
while (h--) {
for (unsigned int ww = w; ww; --ww) {
Expand Down Expand Up @@ -234,6 +251,7 @@ static void gs8_fill_rect(const mp_obj_framebuf_t *fb, unsigned int x, unsigned
static mp_framebuf_p_t formats[] = {
[FRAMEBUF_MVLSB] = {mvlsb_setpixel, mvlsb_getpixel, mvlsb_fill_rect},
[FRAMEBUF_RGB565] = {rgb565_setpixel, rgb565_getpixel, rgb565_fill_rect},
[FRAMEBUF_RGB565_BS] = {rgb565_bs_setpixel, rgb565_bs_getpixel, rgb565_fill_rect},
[FRAMEBUF_GS2_HMSB] = {gs2_hmsb_setpixel, gs2_hmsb_getpixel, gs2_hmsb_fill_rect},
[FRAMEBUF_GS4_HMSB] = {gs4_hmsb_setpixel, gs4_hmsb_getpixel, gs4_hmsb_fill_rect},
[FRAMEBUF_GS8] = {gs8_setpixel, gs8_getpixel, gs8_fill_rect},
Expand Down Expand Up @@ -310,6 +328,7 @@ static mp_obj_t framebuf_make_new_helper(size_t n_args, const mp_obj_t *args_in,
bpp = 8;
break;
case FRAMEBUF_RGB565:
case FRAMEBUF_RGB565_BS:
bpp = 16;
break;
default:
Expand Down Expand Up @@ -909,6 +928,13 @@ static const mp_rom_map_elem_t framebuf_module_globals_table[] = {
{ MP_ROM_QSTR(MP_QSTR_MVLSB), MP_ROM_INT(FRAMEBUF_MVLSB) },
{ MP_ROM_QSTR(MP_QSTR_MONO_VLSB), MP_ROM_INT(FRAMEBUF_MVLSB) },
{ MP_ROM_QSTR(MP_QSTR_RGB565), MP_ROM_INT(FRAMEBUF_RGB565) },
#if MP_ENDIANNESS_LITTLE
{ MP_ROM_QSTR(MP_QSTR_RGB565_LE), MP_ROM_INT(FRAMEBUF_RGB565) },
{ MP_ROM_QSTR(MP_QSTR_RGB565_BE), MP_ROM_INT(FRAMEBUF_RGB565_BS) },
#elif MP_ENDIANNESS_BIG
{ MP_ROM_QSTR(MP_QSTR_RGB565_BE), MP_ROM_INT(FRAMEBUF_RGB565) },
{ MP_ROM_QSTR(MP_QSTR_RGB565_LE), MP_ROM_INT(FRAMEBUF_RGB565_BS) },
#endif // MP_ENDIANNESS_...
{ MP_ROM_QSTR(MP_QSTR_GS2_HMSB), MP_ROM_INT(FRAMEBUF_GS2_HMSB) },
{ MP_ROM_QSTR(MP_QSTR_GS4_HMSB), MP_ROM_INT(FRAMEBUF_GS4_HMSB) },
{ MP_ROM_QSTR(MP_QSTR_GS8), MP_ROM_INT(FRAMEBUF_GS8) },
Expand Down
93 changes: 48 additions & 45 deletions tests/extmod/framebuf16.py
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Original file line number Diff line number Diff line change
Expand Up @@ -4,10 +4,12 @@
print("SKIP")
raise SystemExit

# This test and its .exp file is based on a little-endian architecture.
if sys.byteorder != "little":
print("SKIP")
raise SystemExit
if (sys.byteorder == "little" and framebuf.RGB565 == framebuf.RGB565_LE) or (
sys.byteorder == "big" and framebuf.RGB565 == framebuf.RGB565_BE
):
print("Native format matches expected value.")
else:
print("Unexpected native format.")


def printbuf():
Expand All @@ -17,50 +19,51 @@ def printbuf():
print("-->8--")


w = 4
h = 5
buf = bytearray(w * h * 2)
fbuf = framebuf.FrameBuffer(buf, w, h, framebuf.RGB565)
for format in [framebuf.RGB565_LE, framebuf.RGB565_BE]:
w = 4
h = 5
buf = bytearray(w * h * 2)
fbuf = framebuf.FrameBuffer(buf, w, h, format)

# fill
fbuf.fill(0xFFFF)
printbuf()
fbuf.fill(0x0000)
printbuf()
# fill
fbuf.fill(0xFFFF)
printbuf()
fbuf.fill(0x0000)
printbuf()

# put pixel
fbuf.pixel(0, 0, 0xEEEE)
fbuf.pixel(3, 0, 0xEE00)
fbuf.pixel(0, 4, 0x00EE)
fbuf.pixel(3, 4, 0x0EE0)
printbuf()
# put pixel
fbuf.pixel(0, 0, 0xEEEE)
fbuf.pixel(3, 0, 0xEE00)
fbuf.pixel(0, 4, 0x00EE)
fbuf.pixel(3, 4, 0x0EE0)
printbuf()

# get pixel
print(fbuf.pixel(0, 4), fbuf.pixel(1, 1))
# get pixel
print(fbuf.pixel(0, 4), fbuf.pixel(1, 1))

# scroll
fbuf.fill(0x0000)
fbuf.pixel(2, 2, 0xFFFF)
printbuf()
fbuf.scroll(0, 1)
printbuf()
fbuf.scroll(1, 0)
printbuf()
fbuf.scroll(-1, -2)
printbuf()
# scroll
fbuf.fill(0x0000)
fbuf.pixel(2, 2, 0xFFFF)
printbuf()
fbuf.scroll(0, 1)
printbuf()
fbuf.scroll(1, 0)
printbuf()
fbuf.scroll(-1, -2)
printbuf()

w2 = 2
h2 = 3
buf2 = bytearray(w2 * h2 * 2)
fbuf2 = framebuf.FrameBuffer(buf2, w2, h2, framebuf.RGB565)
w2 = 2
h2 = 3
buf2 = bytearray(w2 * h2 * 2)
fbuf2 = framebuf.FrameBuffer(buf2, w2, h2, format)

fbuf2.fill(0x0000)
fbuf2.pixel(0, 0, 0x0EE0)
fbuf2.pixel(0, 2, 0xEE00)
fbuf2.pixel(1, 0, 0x00EE)
fbuf2.pixel(1, 2, 0xE00E)
fbuf.fill(0xFFFF)
fbuf.blit(fbuf2, 3, 3, 0x0000)
fbuf.blit(fbuf2, -1, -1, 0x0000)
fbuf.blit(fbuf2, 16, 16, 0x0000)
printbuf()
fbuf2.fill(0x0000)
fbuf2.pixel(0, 0, 0x0EE0)
fbuf2.pixel(0, 2, 0xEE00)
fbuf2.pixel(1, 0, 0x00EE)
fbuf2.pixel(1, 2, 0xE00E)
fbuf.fill(0xFFFF)
fbuf.blit(fbuf2, 3, 3, 0x0000)
fbuf.blit(fbuf2, -1, -1, 0x0000)
fbuf.blit(fbuf2, 16, 16, 0x0000)
printbuf()
58 changes: 58 additions & 0 deletions tests/extmod/framebuf16.py.exp
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@@ -1,3 +1,4 @@
Native format matches expected value.
--8<--
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
Expand Down Expand Up @@ -55,3 +56,60 @@ bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\xe0\x0e')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
-->8--
--8<--
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
-->8--
--8<--
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
-->8--
--8<--
bytearray(b'\xee\xee\x00\x00\x00\x00\xee\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\xee\x00\x00\x00\x00\x0e\xe0')
-->8--
238 0
--8<--
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\xff\xff\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
-->8--
--8<--
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\xff\xff\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
-->8--
--8<--
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\xff\xff')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
-->8--
--8<--
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\xff\xff\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
bytearray(b'\x00\x00\x00\x00\x00\x00\xff\xff')
bytearray(b'\x00\x00\x00\x00\x00\x00\x00\x00')
-->8--
--8<--
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xe0\x0e\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
bytearray(b'\xff\xff\xff\xff\xff\xff\x0e\xe0')
bytearray(b'\xff\xff\xff\xff\xff\xff\xff\xff')
-->8--
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