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remove constant ranges from bus, redesign mem map lookups

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Turns out constants in Crystal are slow as _hell_. Thanks Ary for the
help discovering that. Maybe one day Crystal will improve that, but for
now this change over triples performance.
This commit is contained in:
Matthew Berry 2020-10-04 16:10:34 -07:00
parent 800bf36803
commit 493d8b74f6
2 changed files with 34 additions and 23 deletions
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49
src/crab/bus.cr
View file

@ -22,14 +22,22 @@ class Bus
def [](index : Int) : Byte
log "read #{hex_str index.to_u32}"
case index
when WRAM_BOARD then @wram_board[index - WRAM_BOARD.begin]
when WRAM_CHIP then @wram_chip[index - WRAM_CHIP.begin]
when PPU_IO then @gba.ppu[index]
when PPU then @gba.ppu[index]
when CARTRIDGE then @gba.cartridge[index - CARTRIDGE.begin]
when UNUSED then 0xFF_u8
else 0xFF_u8
case bits(index, 24..27)
when 0x2 then @wram_board[index & 0x3FFFF]
when 0x3 then @wram_chip[index & 0x7FFF]
when 0x4
io_addr = 0x0FFF_u16 & index
if io_addr <= 0x05F
@gba.ppu[index]
else
raise "Unmapped i/o read: #{hex_str index.to_u32}"
end
when 0x6
address = 0x1FFFF_u32 & index
address &= ~0x8000 if address > 0x17FFF
@gba.ppu.vram[address]
when 0x8, 0x9 then @gba.cartridge[index & 0x7FFFFFF]
else raise "Unmapped read: #{hex_str index.to_u32}"
end
end
@ -47,14 +55,23 @@ class Bus
def []=(index : Int, value : Byte) : Nil
log "write #{hex_str index.to_u32} -> #{hex_str value}"
case index
when WRAM_BOARD then @wram_board[index - WRAM_BOARD.begin] = value
when WRAM_CHIP then @wram_chip[index - WRAM_CHIP.begin] = value
when PPU_IO then @gba.ppu[index] = value
when PPU then @gba.ppu[index] = value
when CARTRIDGE then @gba.cartridge[index - CARTRIDGE.begin] = value # todo is this meant to be writable?
when UNUSED then nil
else raise "Unimplemented write ~ addr:#{hex_str index.to_u32}, val:#{value}"
return if bits(index, 28..31) > 0
case bits(index, 24..27)
when 0x2 then @wram_board[index & 0x3FFFF] = value
when 0x3 then @wram_chip[index & 0x7FFF] = value
when 0x4
io_addr = 0x0FFF_u16 & index
if io_addr <= 0x05F
@gba.ppu[index] = value
else
raise "Unmapped i/o write: #{hex_str index.to_u32}"
end
when 0x6
address = 0x1FFFF_u32 & index
address &= ~0x8000 if address > 0x17FFF
@gba.ppu.vram[address] = value
when 0x8, 0x9 then @gba.cartridge[index & 0x7FFFFFF] = value
else raise "Unmapped write: #{hex_str index.to_u32}"
end
end

8
src/crab/ppu.cr
View file

@ -1,8 +1,4 @@
class PPU
BG_OBJ_PALETTE = 0x05000000..0x050003FF
VRAM = 0x06000000..0x06017FFF
OAM = 0x07000000..0x070003FF
# Display timings in cycles
HDRAW = 960
HBLANK = 272
@ -29,7 +25,7 @@ class PPU
num bg_mode, 3 # (0-5=Video Mode 0-5, 6-7=Prohibited)
end
@vram = Bytes.new VRAM.size
getter vram = Bytes.new 0x18000
@dispcnt : DISPCNT = DISPCNT.new 0
@ -52,7 +48,6 @@ class PPU
when 0x04000001 then @dispcnt.value.to_u8!
when 0x04000002 then 0_u8
when 0x04000003 then 0_u8
when VRAM then @vram[index = VRAM.begin]
else raise "Unimplemented PPU read ~ addr:#{hex_str index.to_u32}"
end
end
@ -63,7 +58,6 @@ class PPU
when 0x04000001 then @dispcnt.value = (@dispcnt.value & 0xFF00) | value
when 0x04000002
when 0x04000003
when VRAM then @vram[index - VRAM.begin] = value
else raise "Unimplemented PPU write ~ addr:#{hex_str index.to_u32}, val:#{value}"
end
end