ReC98/planar.h

/* ReC98
 * -----
 * Declarations for planar 4bpp graphics
 */

// 1bpp types, describing horizontal lines of 8, 16, or 32 pixels.
typedef uint8_t dots8_t;
typedef uint16_t dots16_t;
typedef uint32_t dots32_t;
// ... and the same for the rare cases where ZUN's code used signed types.
typedef int8_t sdots8_t;
typedef int16_t sdots16_t;
typedef int32_t sdots32_t;

// Defines a hardcoded 1bpp sprite, pre-shifted to all 8 start X positions
// within a single VRAM byte.
#define PRESHIFT BYTE_DOTS

typedef enum {
	PL_B, PL_R, PL_G, PL_E, PL_COUNT
} vram_plane_t;

#ifdef __cplusplus
	template <class T> struct Planar {
		T B, R, G, E;

		T& operator [](int plane) {
			return (&B)[plane];
		}

		const T& operator [](int plane) const {
			return (&B)[plane];
		}
	};
#endif

typedef struct {
	dots8_t B, R, G, E;
} planar8_t;

typedef struct {
	dots16_t B, R, G, E;
} planar16_t;

typedef struct {
	dots32_t B, R, G, E;
} planar32_t;

// Abstracted dot and planar types, with their width defined by a macro.
#define dots_t_(x) dots##x##_t
#define dots_t(x) dots_t_(x)
#define sdots_t_(x) sdots##x##_t
#define sdots_t(x) sdots_t_(x)
#define planar_t_(x) planar##x##_t
#define planar_t(x) planar_t_(x)

// Since array subscripts create slightly different assembly in places, we
// offer both variants.
extern dots8_t *VRAM_PLANE[PL_COUNT];
// And no, expressing these as a struct won't generate the same ASM.
// Been there, tried that.
extern dots8_t *VRAM_PLANE_B;
extern dots8_t *VRAM_PLANE_G;
extern dots8_t *VRAM_PLANE_R;
extern dots8_t *VRAM_PLANE_E;

// Byte offset of an 8-pixel-aligned X/Y position on a VRAM bitplane,
// relative to the beginning (= top-left corner) of the plane.
typedef int16_t vram_offset_t;
// MODDERS: Delete (yes, this one, not the signed one above!)
typedef uint16_t uvram_offset_t;

#define VRAM_OFFSET_SHIFT(x, y) \
	(x >> 3) + (y << 6) + (y << 4)

#ifdef __cplusplus
// MODDERS: Replace with a single function
static inline vram_offset_t vram_offset_shift(screen_x_t x, vram_y_t y)
{
	return VRAM_OFFSET_SHIFT(x, y);
}

static inline vram_offset_t vram_offset_muldiv(screen_x_t x, vram_y_t y)
{
	return (y * ROW_SIZE) + (x / BYTE_DOTS);
}

static inline vram_offset_t vram_offset_divmul(screen_x_t x, vram_y_t y)
{
	return (x / BYTE_DOTS) + (y * ROW_SIZE);
}

static inline vram_offset_t vram_offset_mulshift(screen_x_t x, vram_y_t y)
{
	return (y * ROW_SIZE) + (x >> 3);
}
#endif

#define VRAM_CHUNK(plane, offset, bit_count) \
	*(dots##bit_count##_t *)(VRAM_PLANE_##plane + offset)

#define VRAM_SNAP(dst, plane, offset, bit_count) \
	dst = VRAM_CHUNK(plane, offset, bit_count);

// And no, code generation prohibits these from being turned into nice
// templated class methods. Been there, tried that.
#define VRAM_SNAP_PLANAR(dst, offset, bit_count) \
	VRAM_SNAP(dst.B, B, offset, bit_count); \
	VRAM_SNAP(dst.R, R, offset, bit_count); \
	VRAM_SNAP(dst.G, G, offset, bit_count); \
	VRAM_SNAP(dst.E, E, offset, bit_count);

#define vram_snap_planar_masked(dst, offset, bit_count, mask) \
	dst.B = VRAM_CHUNK(B, offset, bit_count) & mask; \
	dst.R = VRAM_CHUNK(R, offset, bit_count) & mask; \
	dst.G = VRAM_CHUNK(G, offset, bit_count) & mask; \
	dst.E = VRAM_CHUNK(E, offset, bit_count) & mask;

#define VRAM_PUT(plane, offset, src, bit_count) \
	VRAM_CHUNK(plane, offset, bit_count) = src;

#define VRAM_PUT_PLANAR(offset, src, bit_count) \
	VRAM_PUT(B, offset, src.B, bit_count); \
	VRAM_PUT(R, offset, src.R, bit_count); \
	VRAM_PUT(G, offset, src.G, bit_count); \
	VRAM_PUT(E, offset, src.E, bit_count);

#define vram_or_emptyopt(plane, offset, src, bit_count) \
	if(src) { \
		VRAM_CHUNK(plane, offset, bit_count) |= src; \
	}

#define vram_or_masked_emptyopt(plane, offset, bit_count, src, mask) \
	if(src) { \
		VRAM_CHUNK(plane, offset, bit_count) |= (src & mask); \
	}

#define vram_or_planar(offset, src, bit_count) \
	VRAM_CHUNK(B, offset, bit_count) |= src.B; \
	VRAM_CHUNK(R, offset, bit_count) |= src.R; \
	VRAM_CHUNK(G, offset, bit_count) |= src.G; \
	VRAM_CHUNK(E, offset, bit_count) |= src.E;

#define vram_or_planar_emptyopt(offset, src, bit_count) \
	vram_or_emptyopt(B, offset, src.B, bit_count); \
	vram_or_emptyopt(R, offset, src.R, bit_count); \
	vram_or_emptyopt(G, offset, src.G, bit_count); \
	vram_or_emptyopt(E, offset, src.E, bit_count);

#define PLANE_DWORD_BLIT(dst, src) \
	for(p = 0; p < PLANE_SIZE; p += (int)sizeof(dots32_t)) { \
		*(dots32_t*)((dst) + p) = *(dots32_t*)((src) + p); \
	}

void pascal vram_planes_set(void);