Builder state for composing a DRW display list in a caller buffer. More...

#include <ra8_drw.h>

Data Fields
uint32_t *	buf
	Caller word buffer, 4-byte aligned, in SRAM.
uint32_t	cap_words
	Buffer capacity in 32-bit words.
uint32_t	count
	Words emitted so far (<= cap_words).
bool	overflow
	A request exceeded the buffer capacity.
bool	terminated
	ra8_drw_dlist_end has closed the list.

Detailed Description

Builder state for composing a DRW display list in a caller buffer.

A display list lets the DRW clear and repaint a framebuffer end to end with the CPU never touching it inside the loop, so there is no CPU/engine write race to latch STATUS.BUSERRMFB – the loop-stable path proven on silicon for issue #247. ra8_drw_dlist_begin binds this builder to a 4-byte-aligned word buffer in a region the DRW bus initiator can read (SRAM); ra8_drw_dlist_add_fill appends primitives; ra8_drw_dlist_end terminates the list; ra8_drw_dlist_run kicks it. The build calls never touch MMIO.

Invariant: count <= cap_words at all times; overflow latches true if a request would have exceeded cap_words and no partial entry is written.

static uint32_t s_dlist[32];
ra8_drw_dlist_t dl;
ra8_drw_dlist_begin(&dl, s_dlist, 32U);
ra8_drw_dlist_add_fill(&dl, &clear_rect);
ra8_drw_dlist_add_fill(&dl, &box_rect);
ra8_drw_dlist_end(&dl);
ra8_drw_dlist_run(&dl);