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/*
A screen layer contains 768 tiles (32*24), requiring 24KB. Each tile is 32 bytes,
holding 2 pixels per byte. The upper four bits of a tile byte represent the
colour of the right pixel, and the lower four bits the colour of the left pixel.
The colour is a 4-bit reference into a 16-colour RGB15 palette.
Screen memory contains four layers: bg, fg, then the same but for double buffers.
Ignore double buffering for now. We keep these as u32* because a single 32-bit
integer represents a single 8-pixel row.
TODO: This needs to be updated. We have double buffering, and we use u16*.
The tile map is shared by the foreground and background layers, and is stored
just past the first layer for both screens (at the 24KB offset). Each entry is
a 16-bit tile index (low 10 bits are tile index, then h-flip, then v-flip, then
4-bit palette identifier).
*/
#include <nds.h>
#include "screen.h"
#include "../bang.h"
Screen scr_main = {
.bgv = BG_TILE_RAM(BG_SLOT_VIS),
.fgv = BG_TILE_RAM(FG_SLOT_VIS),
.bg = BG_TILE_RAM(BG_SLOT),
.fg = BG_TILE_RAM(FG_SLOT),
.map = BG_MAP_RAM(MAP_SLOT),
.palv = BG_PALETTE,
};
Screen scr_sub = {
.bgv = BG_TILE_RAM_SUB(BG_SLOT_VIS),
.fgv = BG_TILE_RAM_SUB(FG_SLOT_VIS),
.bg = BG_TILE_RAM_SUB(BG_SLOT),
.fg = BG_TILE_RAM_SUB(FG_SLOT),
.map = BG_MAP_RAM_SUB(MAP_SLOT),
.palv = BG_PALETTE_SUB,
};
// TODO: Make an enum thing for main/sub, combine these functions
void scr_make_main(ScreenDevice *scr) {
scr->nds = &scr_main;
for (int i=0; i<16; i++) {
scr->nds->pal[i] = scr->palette[i];
}
scr->wake = true;
}
void scr_make_sub(ScreenDevice *scr) {
scr->nds = &scr_sub;
for (int i=0; i<16; i++) {
scr->nds->pal[i] = scr->palette[i];
}
scr->wake = true;
}
void scr_unmake(ScreenDevice *scr) {
if (scr->nds) {
black_screen(scr->nds);
scr->nds = NULL;
}
}
void init_screens(void) {
// Allocate VRAM for screens
videoSetMode(DISPLAY_BG0_ACTIVE | DISPLAY_BG1_ACTIVE | MODE_0_2D);
vramSetBankA(VRAM_A_MAIN_BG);
videoSetModeSub(DISPLAY_BG0_ACTIVE | DISPLAY_BG1_ACTIVE | MODE_0_2D);
vramSetBankC(VRAM_C_SUB_BG);
/* Configure screen layers to use tile graphics. */
REG_BG0CNT = BG_32x32 | BG_COLOR_16 | BG_PRIORITY_3 | BG_TILE_BASE(BG_SLOT_VIS) | BG_MAP_BASE(MAP_SLOT);
REG_BG1CNT = BG_32x32 | BG_COLOR_16 | BG_PRIORITY_2 | BG_TILE_BASE(FG_SLOT_VIS) | BG_MAP_BASE(MAP_SLOT);
REG_BG0CNT_SUB = BG_32x32 | BG_COLOR_16 | BG_PRIORITY_3 | BG_TILE_BASE(BG_SLOT_VIS) | BG_MAP_BASE(MAP_SLOT);
REG_BG1CNT_SUB = BG_32x32 | BG_COLOR_16 | BG_PRIORITY_2 | BG_TILE_BASE(FG_SLOT_VIS) | BG_MAP_BASE(MAP_SLOT);
/* Populate tile maps with tile indices. */
int i;
u16 *main_map = BG_MAP_RAM(12);
u16 *sub_map = BG_MAP_RAM_SUB(12);
for (i = 0; i < TILES_SIZE; i++) {
*(main_map++) = i;
*(sub_map++) = i;
}
}
void set_palette_high(ScreenDevice *scr, u8 high) {
SET_HIGH(scr->palette_write, high);
}
void set_palette_low(ScreenDevice *scr, u8 low) {
SET_LOW(scr->palette_write, low);
u8 i = scr->palette_write >> 12 & 0x0f;
u8 r = scr->palette_write >> 7 & 0x1e;
u8 g = scr->palette_write >> 3 & 0x1e;
u8 b = scr->palette_write << 1 & 0x1e;
scr->palette[i] = RGB15(r,g,b);
if (scr->nds) {
scr->nds->pal[i] = RGB15(r,g,b);
}
}
void push_sprite(SpriteBuffer *b, u8 row) {
b->mem[b->p] = row;
b->p = (b->p + 1) % 16;
b->cached = FALSE;
}
void prepare_1bit_sprite(SpriteBuffer *b, u8 draw) {
u8 l,p,x,y;
if (b->cached && draw == b->draw) return;
switch (draw & 0x07) {
case 0x0: p=b->p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; for (x=0;x<8;x++) { b->sprite[y][x] = l>>(7-x) & 1; } }; break;
case 0x1: p=b->p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; for (x=0;x<8;x++) { b->sprite[y][x] = l>>( x) & 1; } }; break;
case 0x2: p=b->p; for (y=0;y<8;y++) { l=b->mem[--p % 16]; for (x=0;x<8;x++) { b->sprite[y][x] = l>>(7-x) & 1; } }; break;
case 0x3: p=b->p; for (y=0;y<8;y++) { l=b->mem[--p % 16]; for (x=0;x<8;x++) { b->sprite[y][x] = l>>( x) & 1; } }; break;
case 0x4: p=b->p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; for (x=0;x<8;x++) { b->sprite[x][y] = l>>(7-x) & 1; } }; break;
case 0x5: p=b->p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; for (x=0;x<8;x++) { b->sprite[x][y] = l>>( x) & 1; } }; break;
case 0x6: p=b->p; for (y=0;y<8;y++) { l=b->mem[--p % 16]; for (x=0;x<8;x++) { b->sprite[x][y] = l>>(7-x) & 1; } }; break;
case 0x7: p=b->p; for (y=0;y<8;y++) { l=b->mem[--p % 16]; for (x=0;x<8;x++) { b->sprite[x][y] = l>>( x) & 1; } }; break;
}
b->cached = TRUE;
b->draw = draw;
}
void prepare_2bit_sprite(SpriteBuffer *b, u8 draw) {
u8 l,h,i,p,s,x,y;
if (b->cached && draw == b->draw) return;
switch (draw & 0x07) {
case 0x0: p=b->p+8; s=p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; h=b->mem[s++ % 16]; for (x=0;x<8;x++) { i=(7-x); b->sprite[y][x] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
case 0x1: p=b->p+8; s=p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; h=b->mem[s++ % 16]; for (x=0;x<8;x++) { i=( x); b->sprite[y][x] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
case 0x2: p=b->p; s=p+8; for (y=0;y<8;y++) { l=b->mem[--p % 16]; h=b->mem[--s % 16]; for (x=0;x<8;x++) { i=(7-x); b->sprite[y][x] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
case 0x3: p=b->p; s=p+8; for (y=0;y<8;y++) { l=b->mem[--p % 16]; h=b->mem[--s % 16]; for (x=0;x<8;x++) { i=( x); b->sprite[y][x] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
case 0x4: p=b->p+8; s=p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; h=b->mem[s++ % 16]; for (x=0;x<8;x++) { i=(7-x); b->sprite[x][y] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
case 0x5: p=b->p+8; s=p+8; for (y=0;y<8;y++) { l=b->mem[p++ % 16]; h=b->mem[s++ % 16]; for (x=0;x<8;x++) { i=( x); b->sprite[x][y] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
case 0x6: p=b->p; s=p+8; for (y=0;y<8;y++) { l=b->mem[--p % 16]; h=b->mem[--s % 16]; for (x=0;x<8;x++) { i=(7-x); b->sprite[x][y] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
case 0x7: p=b->p; s=p+8; for (y=0;y<8;y++) { l=b->mem[--p % 16]; h=b->mem[--s % 16]; for (x=0;x<8;x++) { i=( x); b->sprite[x][y] = (l>>i & 1) | (h>>i & 1) << 1; } }; break;
}
b->cached = TRUE;
b->draw = draw;
}
// ---------------------------------------------------------------------------
void draw_pixel(u16 *layer, u16 x, u16 y, u8 colour) {
if (x < PIXELS_WIDTH && y < PIXELS_HEIGHT) {
u32 addr = \
(x >> 2 & 0x0001) + (x << 1 & 0xfff0) + \
(y << 1 & 0x000f) + (y << 6 & 0xfe00);
u16 shift = (x & 0x3) << 2;
layer[addr] = (layer[addr] & ~(0xf << shift)) | (colour << shift);
}
}
void fill_layer(u16 *layer, u8 colour) {
u8 byte = colour << 4 | colour;
u32 word = byte << 24 | byte << 16 | byte << 8 | byte;
dmaFillWords(word, layer, TILES_MEM);
}
void erase_screen(Screen *nds) {
if (nds) {
dmaFillWords(0, nds->bg, TILES_MEM);
dmaFillWords(0, nds->fg, TILES_MEM);
}
};
void flip_buffer(Screen *nds) {
if (nds) {
dmaCopyWords(0, nds->bg, nds->bgv, TILES_MEM);
dmaCopyWords(0, nds->fg, nds->fgv, TILES_MEM);
for (int i=0; i<16; i++) {
nds->palv[i] = nds->pal[i];
}
}
}
void black_screen(Screen *nds) {
if (nds) {
for (int i=0; i<16; i++) {
nds->palv[i] = RGB15(0,0,0);
}
dmaFillWords(0, nds->bgv, TILES_MEM);
dmaFillWords(0, nds->fgv, TILES_MEM);
}
}
// ---------------------------------------------------------------------------
void draw_dispatch(ScreenDevice *scr, u8 draw) {
if (scr->nds) {
switch (draw >> 4) {
case 0x0: scr_draw_pixel(scr, scr->nds->bg, draw); break;
case 0x1: scr_draw_sprite(scr, scr->nds->bg, draw); break;
case 0x2: scr_fill_layer(scr, scr->nds->bg, draw); break;
case 0x3: scr_draw_sprite(scr, scr->nds->bg, draw); break;
case 0x4: scr_draw_line(scr, scr->nds->bg, draw); break;
case 0x5: scr_draw_line(scr, scr->nds->bg, draw); break;
case 0x6: scr_draw_rect(scr, scr->nds->bg, draw); break;
case 0x7: scr_draw_rect(scr, scr->nds->bg, draw); break;
case 0x8: scr_draw_pixel(scr, scr->nds->fg, draw); break;
case 0x9: scr_draw_sprite(scr, scr->nds->fg, draw); break;
case 0xA: scr_fill_layer(scr, scr->nds->fg, draw); break;
case 0xB: scr_draw_sprite(scr, scr->nds->fg, draw); break;
case 0xC: scr_draw_line(scr, scr->nds->fg, draw); break;
case 0xD: scr_draw_line(scr, scr->nds->fg, draw); break;
case 0xE: scr_draw_rect(scr, scr->nds->fg, draw); break;
case 0xF: scr_draw_rect(scr, scr->nds->fg, draw); break;
}
scr->dirty = true;
}
scr->px = scr->x;
scr->py = scr->y;
}
void scr_draw_pixel(ScreenDevice *scr, u16 *layer, u8 draw) {
draw_pixel(layer, scr->x, scr->y, draw&0xf);
}
void scr_fill_layer(ScreenDevice *scr, u16 *layer, u8 draw) {
fill_layer(layer, draw&0xf);
}
void scr_draw_sprite(ScreenDevice *scr, u16 *layer, u8 draw) {
if (draw & 0x20) { prepare_2bit_sprite(&scr->sprite, draw); }
else { prepare_1bit_sprite(&scr->sprite, draw); }
u8 colours[4] = {
scr->colours >> 12 & 0x000f,
scr->colours >> 8 & 0x000f,
scr->colours >> 4 & 0x000f,
scr->colours & 0x000f,
};
if (draw & 0x08) {
// Draw sprite with transparent background
for (u8 y=0;y<8;y++) {
for (u8 x=0;x<8;x++) {
u8 i = scr->sprite.sprite[y][x];
if (i) draw_pixel(layer, scr->x+x, scr->y+y, colours[i]);
}
}
} else {
// Draw sprite with opaque background
for (u8 y=0;y<8;y++) {
for (u8 x=0;x<8;x++) {
u8 i = scr->sprite.sprite[y][x];
draw_pixel(layer, scr->x+x, scr->y+y, colours[i]);
}
}
}
}
void scr_draw_line(ScreenDevice *scr, u16 *layer, u8 draw) {
s16 x = (s16) scr->x;
s16 y = (s16) scr->y;
s16 x_end = (s16) scr->px;
s16 y_end = (s16) scr->py;
s32 dx = abs(x_end - x);
s32 dy = -abs(y_end - y);
s16 sx = x < x_end ? 1 : -1;
s16 sy = y < y_end ? 1 : -1;
s32 e1 = dx + dy;
if (draw & 0x10) {
// Draw 1-bit textured line.
prepare_1bit_sprite(&scr->sprite, draw);
u8 c1 = scr->colours >> 8 & 0xf;
u8 c0 = scr->colours >> 12 & 0xf;
bool opaque = !(draw & 0x08);
while (1) {
if (scr->sprite.sprite[y%8][x%8]) { draw_pixel(layer, x, y, c1); }
else if (opaque) { draw_pixel(layer, x, y, c0); }
if (x == x_end && y == y_end) return;
s32 e2 = e1 << 1;
if (e2 >= dy) { e1 += dy; x += sx; }
if (e2 <= dx) { e1 += dx; y += sy; }
}
} else {
// Draw solid line.
u8 colour = draw & 0xf;
while (1) {
draw_pixel(layer, x, y, colour);
if (x == x_end && y == y_end) return;
s32 e2 = e1 << 1;
if (e2 >= dy) { e1 += dy; x += sx; }
if (e2 <= dx) { e1 += dx; y += sy; }
}
}
}
void scr_draw_rect(ScreenDevice *scr, u16 *layer, u8 draw) {
#define SWAP(x,y) {u8 temp=x; x=y; y=temp;}
#define CLAMP(v,m) {v>0x7fff ? 0 : v>m ? m : v}
// Get bounding box.
u16 l = CLAMP(scr->px, PIXELS_WIDTH -1);
u16 r = CLAMP(scr->x , PIXELS_WIDTH -1);
u16 t = CLAMP(scr->py, PIXELS_HEIGHT-1);
u16 b = CLAMP(scr->y , PIXELS_HEIGHT-1);
if (l>r) SWAP(l,r);
if (t>b) SWAP(t,b);
if (draw & 0x10) {
// Draw 1-bit textured rectangle.
prepare_1bit_sprite(&scr->sprite, draw);
u8 c1 = scr->colours >> 8 & 0xf;
u8 c0 = scr->colours >> 12 & 0xf;
bool opaque = !(draw & 0x08);
for (u16 x=l; x<r+1; x++) {
for (u16 y=t; y<b+1; y++) {
if (scr->sprite.sprite[y%8][x%8]) { draw_pixel(layer, x, y, c1); }
else if (opaque) { draw_pixel(layer, x, y, c0); }
}
}
} else {
// Draw solid rectangle.
u8 colour = draw & 0xf;
for (u16 x=l; x<r+1; x++) {
for (u16 y=t; y<b+1; y++) {
draw_pixel(layer, x, y, colour);
}
}
}
}
void move_cursor(ScreenDevice *scr, u8 move) {
switch (move >> 6) {
case 0b00: scr->x += move & 0x3f; return;
case 0b01: scr->y += move & 0x3f; return;
case 0b10: scr->x -= move & 0x3f; return;
case 0b11: scr->y -= move & 0x3f; return;
}
}
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