#include <vhex/defs/types.h>
#include <vhex/driver.h>
#include <vhex/driver/screen/r61524.h>
#include <vhex/display/stack.h>

//---
// R61524 driver API
//---

/* r61524_clear_surface() - optimal way to clear the draw and render surface */
VINLINE void r61524_clear_surface(struct dshader_surface *surface)
{
	uint32_t *xram = surface->draw;
	int size = (surface->y1 == 220) ? 792 : 1980;

	for (int i = 0; i < size; ++i) {
		xram[i] = 0x00010001;
	}
}

/* r61524_frame_start() - prepar the screen and reset surfaces */
int r61524_frame_start(struct dshader_surface *surface)
{
	/* Set the windows size */
	r61524_select(horizontal_ram_start);
	r61524_write(0);
	r61524_select(horizontal_ram_end);
	r61524_write(395);
	r61524_select(vertical_ram_start);
	r61524_write(0);
	r61524_select(vertical_ram_end);
	r61524_write(223);

	/* Set the RAM position */
	r61524_select(ram_address_horizontal);
	r61524_write(0);
	r61524_select(ram_address_vertical);
	r61524_write(0);

	/* Bind address 0xb4000000 to the data write command */
	r61524_select(write_data);

	/* initialize surface information */
	surface->draw = (void*)0xe5007000;
	surface->frag = (void*)0xe5017000;
	surface->width = 396;
	surface->height = 10;
	surface->x1 = 0;
	surface->y1 = 0;
	surface->x2 = 395;
	surface->y2 = 9;

	/* reset the two surfaces */
	r61524_clear_surface(surface);
	return (0);
}

int r61524_frame_frag_next(struct dshader_surface *surface)
{
	surface->y1 += 10;
	if (surface->y1 >= 224) {
		surface->y1 -= 10;
		return (-1);
	}

	if (surface->y1 >= 220)
		surface->height = 4;
	surface->y2 += surface->height;
	return (0);
}

VWEAK int r61524_frame_frag_send(struct dshader_surface *surface)
{
	uint16_t * restrict yram = surface->frag;
	int size = (surface->y1 == 220) ? 1584 : 3960;

	for (int i = 0; i < size; ++i) {
		r61524_write(yram[i]);
	}
	return (0);
}

int r61524_frame_end(struct dshader_surface *surface)
{
	(void)surface;
	return (0);
}

//---
// Driver definition
//---

/* R61524 display (graphics RAM range) */
struct r61524_ctx {
	uint16_t HSA;
	uint16_t HEA;
	uint16_t VSA;
	uint16_t VEA;
};

static void __r61524_configure(struct r61524_ctx *s)
{
	s->HSA = 0;
	s->HEA = 395;
	s->VSA = 0;
	s->VEA = 223;
}

static void __r61524_hsave(struct r61524_ctx *s)
{
	r61524_select(horizontal_ram_start);
	s->HSA = r61524_read();
	r61524_select(horizontal_ram_end);
	s->HEA = r61524_read();

	r61524_select(vertical_ram_start);
	s->VSA = r61524_read();
	r61524_select(vertical_ram_end);
	s->VEA = r61524_read();
}

static void __r61524_hrestore(struct r61524_ctx const *s)
{
	r61524_select(horizontal_ram_start);
	r61524_write(s->HSA);
	r61524_select(horizontal_ram_end);
	r61524_write(s->HEA);

	r61524_select(vertical_ram_start);
	r61524_write(s->VSA);
	r61524_select(vertical_ram_end);
	r61524_write(s->VEA);
}


struct vhex_driver drv_r61524 = {
	.name       = "R61524",
	.hsave      = (void*)&__r61524_hsave,
	.hrestore   = (void*)&__r61524_hrestore,
	.configure  = (void*)&__r61524_configure,
	.state_size = sizeof(struct r61524_ctx),
	.flags = {
		.DISPLAY = 1,
		.SHARED  = 0,
		.UNUSED  = 0,
	},
	.module_data = &(struct dstack_drv_interface){
		.frame_start     = &r61524_frame_start,
		.frame_frag_next = &r61524_frame_frag_next,
		.frame_frag_send = &r61524_frame_frag_send,
		.frame_end       = &r61524_frame_end,
		.display_width   = 396,
		.display_height  = 224
	}
};
VHEX_DECLARE_DRIVER(16, drv_r61524);