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NES: Small PPU optimization
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@ducalex @kbeckmann
ducalex authored and kbeckmann committed Jan 11, 2021
1 parent 786191d commit 7b49579
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Showing 2 changed files with 40 additions and 58 deletions.
94 changes: 38 additions & 56 deletions nofrendo-go/components/nofrendo/nes/nes_ppu.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -114,7 +114,6 @@ void ppu_setpage(int size, int page_num, uint8 *location)
}
}

/* bleh, for snss */
uint8 *ppu_getpage(int page)
{
return ppu.page[page];
Expand Down Expand Up @@ -574,36 +573,28 @@ INLINE void draw_oamtile(uint8 *surface, uint8 attrib, uint16 pattern, const uin

INLINE void ppu_renderbg(uint8 *vidbuf)
{
uint8 *bmp_ptr;
int32 refresh_vaddr, tile_addr, bg_offset, attrib_base, attrib_addr;
uint8 tile_index, tile_num, x_tile, y_tile, col_high, attrib, attrib_shift;

/* draw a line of transparent background color if bg is disabled */
if (false == ppu.bg_on)
{
memset(vidbuf, FULLBG, NES_SCREEN_WIDTH);
return;
}

bmp_ptr = vidbuf - ppu.tile_xofs; /* scroll x */
refresh_vaddr = 0x2000 + (ppu.vaddr & 0x0FE0); /* mask out x tile */
x_tile = ppu.vaddr & 0x1F;
y_tile = (ppu.vaddr >> 5) & 0x1F; /* to simplify calculations */
bg_offset = ((ppu.vaddr >> 12) & 7) + ppu.bg_base; /* offset in y tile */

/* calculate initial values */
tile_addr = refresh_vaddr + x_tile; /* pointer to tile index */
attrib_base = (refresh_vaddr & 0x2C00) + 0x3C0 + ((y_tile & 0x1C) << 1);
attrib_addr = attrib_base + (x_tile >> 2);
attrib = PPU_MEM_READ(attrib_addr); attrib_addr++;
attrib_shift = (x_tile & 2) + ((y_tile & 2) << 1);
col_high = ((attrib >> attrib_shift) & 3) << 2;
uint8 *bmp_ptr = vidbuf - ppu.tile_xofs; /* scroll x */
uint x_tile = ppu.vaddr & 0x1F;
uint refresh_vaddr = 0x2000 + (ppu.vaddr & 0x0FE0); /* mask out x tile */
uint bg_offset = ((ppu.vaddr >> 12) & 7) + ppu.bg_base; /* offset in y tile */
uint attrib_base = (refresh_vaddr & 0x2C00) + 0x3C0 + (((ppu.vaddr >> 5) & 0x1C) << 1);
uint attrib_addr = attrib_base + (x_tile >> 2);
uint attrib = PPU_MEM_READ(attrib_addr); attrib_addr++;
uint attrib_shift = (x_tile & 2) + (((ppu.vaddr >> 5) & 2) << 1);
uint col_high = ((attrib >> attrib_shift) & 3) << 2;

/* ppu fetches 33 tiles */
for (tile_num = 0; tile_num < 33; tile_num++)
for (int tile_num = 0; tile_num < 33; tile_num++)
{
/* Tile number from nametable */
tile_index = PPU_MEM_READ(tile_addr); tile_addr++;
int tile_index = PPU_MEM_READ(refresh_vaddr + x_tile);

/* Handle $FD/$FE tile VROM switching (PunchOut) */
if (ppu.latchfunc)
Expand All @@ -624,9 +615,6 @@ INLINE void ppu_renderbg(uint8 *vidbuf)
x_tile = 0;
refresh_vaddr ^= (1 << 10); /* switch nametable */
attrib_base ^= (1 << 10);

/* recalculate pointers */
tile_addr = refresh_vaddr;
attrib_addr = attrib_base;
}

Expand All @@ -650,26 +638,21 @@ INLINE void ppu_renderbg(uint8 *vidbuf)
/* TODO: fetch valid OAM a scanline before, like the Real Thing */
INLINE void ppu_renderoam(uint8 *vidbuf, int scanline, bool draw)
{
int32 sprite_num, sprite_offset, sprite_height, count;
int32 y_offset, tile_addr, sprite_y, savecol1, savecol2;
ppu_obj_t *sprite;

if (false == ppu.obj_on)
return;

/* Save left hand column */
savecol1 = ((int32 *) vidbuf)[0];
savecol2 = ((int32 *) vidbuf)[1];
uint32 savecol1 = ((uint32 *) vidbuf)[0];
uint32 savecol2 = ((uint32 *) vidbuf)[1];

/* Sprite position */
sprite_height = ppu.obj_height;
sprite_offset = ppu.obj_base;
int sprite_height = ppu.obj_height;
int sprite_offset = ppu.obj_base;

sprite = (ppu_obj_t *) ppu.oam;

for (sprite_num = 0, count = 0; sprite_num < 64; sprite_num++, sprite++)
for (int sprite_num = 0, count = 0; sprite_num < 64; sprite_num++)
{
sprite_y = sprite->y_loc + 1;
ppu_obj_t *sprite = (ppu_obj_t *)ppu.oam + sprite_num;

int sprite_y = sprite->y_loc + 1;

/* Check to see if sprite is out of range */
if ((sprite_y > scanline) || (sprite_y <= (scanline - sprite_height))
Expand All @@ -680,6 +663,8 @@ INLINE void ppu_renderoam(uint8 *vidbuf, int scanline, bool draw)
if (ppu.latchfunc)
ppu.latchfunc(sprite_offset, sprite->tile);

int tile_addr, y_offset;

/* 8x16 even sprites use $0000, odd use $1000 */
if (16 == sprite_height)
tile_addr = ((sprite->tile & 1) << 12) | ((sprite->tile & 0xFE) << 4);
Expand Down Expand Up @@ -717,7 +702,10 @@ INLINE void ppu_renderoam(uint8 *vidbuf, int scanline, bool draw)
return;

/* Fetch tile and draw it */
draw_oamtile(vidbuf + sprite->x_loc, sprite->attr, get_patpix(tile_addr),
draw_oamtile(
vidbuf + sprite->x_loc,
sprite->attr,
get_patpix(tile_addr),
ppu.palette + 16 + ((sprite->attr & 3) << 2));

/* maximum of 8 sprites per scanline */
Expand All @@ -731,8 +719,8 @@ INLINE void ppu_renderoam(uint8 *vidbuf, int scanline, bool draw)
/* Restore lefthand column */
if (!ppu.left_obj_on)
{
((int32 *) vidbuf)[0] = savecol1;
((int32 *) vidbuf)[1] = savecol2;
((uint32 *) vidbuf)[0] = savecol1;
((uint32 *) vidbuf)[1] = savecol2;
}
}

Expand All @@ -751,26 +739,21 @@ IRAM_ATTR void ppu_endscanline()
/* modify vram address at end of scanline */
if (ppu.scanline < 240 && (ppu.bg_on || ppu.obj_on))
{
int ytile;

/* check for max 3 bit y tile offset */
if (7 == (ppu.vaddr >> 12))
{
ppu.vaddr &= ~0x7000; /* clear y tile offset */
ytile = (ppu.vaddr >> 5) & 0x1F;

if (29 == ytile)
{
ppu.vaddr &= ~0x03E0; /* clear y tile */
ppu.vaddr ^= 0x0800; /* toggle nametable */
}
else if (31 == ytile)
{
ppu.vaddr &= ~0x03E0; /* clear y tile */
}
else
switch ((ppu.vaddr >> 5) & 0x1F)
{
ppu.vaddr += 0x20; /* increment y tile */
case 29:
ppu.vaddr &= ~0x73E0; /* clear y tile and offset */
ppu.vaddr ^= 0x0800; /* toggle nametable */
break;
case 31:
ppu.vaddr &= ~0x73E0; /* clear y tile and offset */
break;
default:
ppu.vaddr &= ~0x7000; /* clear y tile offset */
ppu.vaddr += 0x20; /* increment y tile */
}
}
else
Expand Down Expand Up @@ -904,7 +887,6 @@ INLINE void draw_deadsprite(bitmap_t *bmp, int x, int y, int height)
}
}

/* Stuff for the OAM viewer */
INLINE void draw_sprite(bitmap_t *bmp, int x, int y, uint8 tile_num, uint8 attrib)
{
int line, height;
Expand Down
4 changes: 2 additions & 2 deletions nofrendo-go/main/main.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,7 @@ static odroid_video_frame_t *currentUpdate = &update1;
static odroid_video_frame_t *previousUpdate = NULL;

static int16_t audioBuffer[AUDIO_BUFFER_LENGTH * 2];
static int16_t pendingSamples = 0;
static int32_t pendingSamples = 0;

static odroid_gamepad_state_t joystick1;
static odroid_gamepad_state_t joystick2;
Expand Down Expand Up @@ -291,7 +291,7 @@ void osd_wait_for_vsync()
*/
void osd_audioframe(int audioSamples)
{
if (odroid_system_get_app()->speedupEnabled)
if (app->speedupEnabled)
return;

apu_process(audioBuffer, audioSamples); //get audio data
Expand Down

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