UYVY-to-RGB888 conversion and 0/90/180/270 SDRAM image production. More...

#include "cam_image.h"
#include <stdint.h>
#include "ra8_cache.h"
#include "ra8_check.h"

Include dependency graph for cam_image.c:

Data Structures
struct	cam_rgb_t
	One RGB888 pixel used while scattering the four orientations. More...

Enumerations
enum	cam_image_align_t : uint32_t { k_cam_image_cache_line_bytes = 32U }
	Cache-line alignment shared by the SDRAM buffers and cache API. More...
enum	cam_image_yuv_coeff_t : int32_t { k_cam_yuv_luma_black = 16 , k_cam_yuv_chroma_mid = 128 , k_cam_yuv_luma_scale = 298 , k_cam_yuv_red_cr = 409 , k_cam_yuv_green_cb = 100 , k_cam_yuv_green_cr = 208 , k_cam_yuv_blue_cb = 516 , k_cam_yuv_rounding = 128 , k_cam_yuv_shift = 8 }
	BT.601 limited-range fixed-point YCbCr-to-RGB coefficients. More...

Functions
static uint8_t	cam_image_clamp (int32_t component)
	Clamp a signed RGB component to one byte.
static cam_rgb_t	cam_image_ycbcr_to_rgb (uint8_t y, uint8_t cb, uint8_t cr)
	Convert one limited-range YCbCr pixel to RGB888.
static void	cam_image_scatter (uint32_t x, uint32_t y, cam_rgb_t rgb)
	Write one RGB pixel to all four rotated row-major destinations.
static void	cam_image_convert (const uint8_t *uyvy)
	Convert one complete UYVY frame into all four RGB orientations.
static ra8_err_t	cam_image_clean_outputs (void)
	Clean all generated RGB views from the data cache.
ra8_err_t	cam_image_generate (const uint8_t *uyvy, uint32_t source_bytes)
	Convert one packed Cb-Y0-Cr-Y1 VGA frame into all four RGB views.

Variables
uint8_t	g_cam_rgb_0 [k_cam_rgb_frame_bytes]
	Unrotated 640x480 RGB888 image in external SDRAM.
uint8_t	g_cam_rgb_90 [k_cam_rgb_frame_bytes]
	Clockwise-90-degree 480x640 RGB888 image in external SDRAM.
uint8_t	g_cam_rgb_180 [k_cam_rgb_frame_bytes]
	Clockwise-180-degree 640x480 RGB888 image in external SDRAM.
uint8_t	g_cam_rgb_270 [k_cam_rgb_frame_bytes]
	Clockwise-270-degree 480x640 RGB888 image in external SDRAM.
const uint32_t	g_cam_rgb_frame_bytes = (uint32_t)k_cam_rgb_frame_bytes
	Stable byte count of each exported RGB888 buffer.

Detailed Description

UYVY-to-RGB888 conversion and 0/90/180/270 SDRAM image production.

Converts one module-owned packed VGA frame into four statically allocated, cache-aligned RGB888 SDRAM views and performs cache maintenance for debugger-side validation.

Tag: [Ring 6 / APP] {World: S}

Copyright: Copyright (c) 2026 Brighton Sikarskie SPDX-License-Identifier: MIT

Since: 0.1.0

Definition in file cam_image.c.

Enumeration Type Documentation

◆ cam_image_align_t

enum cam_image_align_t : uint32_t

Cache-line alignment shared by the SDRAM buffers and cache API.

Enumerator
k_cam_image_cache_line_bytes	Cortex-M85 data-cache line size.

Definition at line 24 of file cam_image.c.

◆ cam_image_yuv_coeff_t

enum cam_image_yuv_coeff_t : int32_t

BT.601 limited-range fixed-point YCbCr-to-RGB coefficients.

Enumerator
k_cam_yuv_luma_black	Limited-range black luma code.
k_cam_yuv_chroma_mid	Neutral limited-range chroma code.
k_cam_yuv_luma_scale	BT.601 fixed-point luma coefficient.
k_cam_yuv_red_cr	BT.601 red-from-Cr coefficient.
k_cam_yuv_green_cb	BT.601 green-from-Cb coefficient.
k_cam_yuv_green_cr	BT.601 green-from-Cr coefficient.
k_cam_yuv_blue_cb	BT.601 blue-from-Cb coefficient.
k_cam_yuv_rounding	Fixed-point rounding bias.
k_cam_yuv_shift	Fixed-point fractional-bit count.

Definition at line 29 of file cam_image.c.

Function Documentation

◆ cam_image_clamp()

uint8_t cam_image_clamp ( int32_t component )

static

Clamp a signed RGB component to one byte.

Saturates negative and over-range fixed-point conversion results.

Parameters

[in] component Signed RGB channel value.

Returns: Saturated channel byte.

Return values

0	The component was negative.
UINT8_MAX	The component exceeded one byte.

Precondition: component is a completed fixed-point conversion result.; No mutable image state is required.

Postcondition: The return value lies in the inclusive byte range.; No global storage is modified.

Note: In-range values are converted without scaling.

Since: 0.1.0

Definition at line 73 of file cam_image.c.

Referenced by cam_image_ycbcr_to_rgb().

◆ cam_image_clean_outputs()

ra8_err_t cam_image_clean_outputs ( void )

static

Clean all generated RGB views from the data cache.

Returns: Status of the first failed cache-clean operation.

Return values

k_ra8_ok All four image ranges were cleaned.

Precondition: cam_image_convert populated every RGB view.

Postcondition: Successful completion makes every RGB view visible outside the CPU.

Note: Thread safety: not thread-safe; operates on module-owned buffers.

Since: 0.1.0

Definition at line 194 of file cam_image.c.

References g_cam_rgb_0, g_cam_rgb_180, g_cam_rgb_270, g_cam_rgb_90, k_cam_rgb_frame_bytes, ra8_cache_dcache_clean_by_addr(), and RA8_RETURN_ON_ERROR.

Referenced by cam_image_generate().

◆ cam_image_convert()

void cam_image_convert ( const uint8_t * uyvy )

static

Convert one complete UYVY frame into all four RGB orientations.

Parameters

[in] uyvy Complete VGA UYVY source frame.

Precondition: uyvy points to at least k_cam_uyvy_frame_bytes readable bytes.

Postcondition: All four statically allocated RGB buffers contain complete views.

Note: Thread safety: not thread-safe; writes module-owned image buffers.

Since: 0.1.0

Definition at line 167 of file cam_image.c.

References cam_image_scatter(), cam_image_ycbcr_to_rgb(), k_cam_image_height_px, and k_cam_image_width_px.

Referenced by cam_image_generate().

◆ cam_image_generate()

ra8_err_t cam_image_generate	(	const uint8_t *	uyvy,
		uint32_t	source_bytes )

Convert one packed Cb-Y0-Cr-Y1 VGA frame into all four RGB views.

Performs fixed-point YCbCr conversion and scatters each pixel into caller-observable SDRAM buffers for the four clockwise orientations.

Parameters

[in]	uyvy	Source VGA frame in packed UYVY byte order.
[in]	source_bytes	Valid bytes at uyvy; must equal 614400.

Returns: Error code from validation or cache maintenance.

Return values

k_ra8_ok	Four complete RGB888 buffers are visible to SWD.
k_ra8_err_null_ptr	uyvy was NULL.
k_ra8_err_invalid_arg	source_bytes was not one VGA UYVY frame.

Precondition: External SDRAM was initialized by ra8_sdramc_init.; uyvy contains a completed, cache-coherent CEU capture.

Postcondition: All four exported buffers contain the same frame at 0/90/180/270.; Dirty D-cache lines covering the four buffers are written to SDRAM.

Note: Rotation angles are clockwise. Not thread-safe.

Since: 0.1.0

Definition at line 209 of file cam_image.c.

References cam_image_clean_outputs(), cam_image_convert(), k_cam_uyvy_frame_bytes, k_ra8_err_invalid_arg, and RA8_CHECK_NULL_PTR.

Referenced by cam_finish_verdict().

◆ cam_image_scatter()

void cam_image_scatter	(	uint32_t	x,
		uint32_t	y,
		cam_rgb_t	rgb )

static

Write one RGB pixel to all four rotated row-major destinations.

Computes the 0, 90, 180, and 270 degree row-major offsets once.

Parameters

[in]	x	Source-frame horizontal coordinate.
[in]	y	Source-frame vertical coordinate.
[in]	rgb	Pixel value to scatter.

Precondition: x and y are inside the VGA source dimensions.; All four SDRAM output arrays are writable.

Postcondition: Each orientation receives exactly one RGB pixel.; No output byte outside the four computed pixels is modified.

Note: Rotation angles are clockwise.

Since: 0.1.0

Definition at line 136 of file cam_image.c.

References cam_rgb_t::blue, g_cam_rgb_0, g_cam_rgb_180, g_cam_rgb_270, g_cam_rgb_90, cam_rgb_t::green, k_cam_image_height_px, k_cam_image_width_px, k_cam_rgb_bytes_per_px, and cam_rgb_t::red.

Referenced by cam_image_convert().

◆ cam_image_ycbcr_to_rgb()

cam_rgb_t cam_image_ycbcr_to_rgb	(	uint8_t	y,
		uint8_t	cb,
		uint8_t	cr )

static

Convert one limited-range YCbCr pixel to RGB888.

Applies fixed-point BT.601-style luma and chroma coefficients.

Parameters

[in]	y	Limited-range luma byte.
[in]	cb	Blue-difference chroma byte.
[in]	cr	Red-difference chroma byte.

Returns: Converted RGB pixel.

Return values

cam_rgb_t Saturated red, green, and blue channels.

Precondition: Input components are sampled from one packed UYVY pair.; Fixed-point coefficient constants retain their configured scale.

Postcondition: Each returned channel lies in the byte range.; Input values and global buffers remain unchanged.

Note: Conversion uses integer arithmetic only.

Since: 0.1.0

Definition at line 99 of file cam_image.c.

References cam_image_clamp(), k_cam_yuv_blue_cb, k_cam_yuv_chroma_mid, k_cam_yuv_green_cb, k_cam_yuv_green_cr, k_cam_yuv_luma_black, k_cam_yuv_luma_scale, k_cam_yuv_red_cr, k_cam_yuv_rounding, and k_cam_yuv_shift.

Referenced by cam_image_convert().

Variable Documentation

◆ g_cam_rgb_0

uint8_t g_cam_rgb_0[k_cam_rgb_frame_bytes]

Unrotated 640x480 RGB888 image in external SDRAM.

Since: 0.1.0

Definition at line 49 of file cam_image.c.

Referenced by cam_image_clean_outputs(), and cam_image_scatter().

◆ g_cam_rgb_180

uint8_t g_cam_rgb_180[k_cam_rgb_frame_bytes]

Clockwise-180-degree 640x480 RGB888 image in external SDRAM.

Since: 0.1.0

Definition at line 53 of file cam_image.c.

Referenced by cam_image_clean_outputs(), and cam_image_scatter().

◆ g_cam_rgb_270

uint8_t g_cam_rgb_270[k_cam_rgb_frame_bytes]

Clockwise-270-degree 480x640 RGB888 image in external SDRAM.

Since: 0.1.0

Definition at line 55 of file cam_image.c.

Referenced by cam_image_clean_outputs(), and cam_image_scatter().

◆ g_cam_rgb_90

uint8_t g_cam_rgb_90[k_cam_rgb_frame_bytes]

Clockwise-90-degree 480x640 RGB888 image in external SDRAM.

Since: 0.1.0

Definition at line 51 of file cam_image.c.

Referenced by cam_image_clean_outputs(), and cam_image_scatter().

◆ g_cam_rgb_frame_bytes

const uint32_t g_cam_rgb_frame_bytes = (uint32_t)k_cam_rgb_frame_bytes

Stable byte count of each exported RGB888 buffer.

Since: 0.1.0

Definition at line 57 of file cam_image.c.

Referenced by cam_finish_verdict().

Data Structures

Enumerations

Functions

Variables

Detailed Description

Enumeration Type Documentation

◆ cam_image_align_t

◆ cam_image_yuv_coeff_t

Function Documentation

◆ cam_image_clamp()

◆ cam_image_clean_outputs()

◆ cam_image_convert()

◆ cam_image_generate()

◆ cam_image_scatter()

◆ cam_image_ycbcr_to_rgb()

Variable Documentation

◆ g_cam_rgb_0

◆ g_cam_rgb_180

◆ g_cam_rgb_270

◆ g_cam_rgb_90

◆ g_cam_rgb_frame_bytes