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rough pass at access timing to improve performance
This commit is contained in:
Matthew Berry
parent
94aa84d53b
commit
bbfdd90fb8
2 changed files with 104 additions and 51 deletions
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@ -1,5 +1,12 @@
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module GBA
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class Bus
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# Timings for rom are estimated for game compatibility.
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ACCESS_TIMING_TABLE = [
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[1, 1, 3, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2], # 8-bit and 16-bit accesses
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[1, 1, 6, 1, 1, 2, 2, 1, 4, 4, 4, 4, 4, 4, 4, 4], # 32-bit accesses
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]
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property cycles = 0
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getter bios = Bytes.new 0x4000
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getter wram_board = Bytes.new 0x40000
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getter wram_chip = Bytes.new 0x08000
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@ -9,6 +16,65 @@ module GBA
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end
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def [](index : Int) : Byte
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@cycles += ACCESS_TIMING_TABLE[0][page(index)]
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read_byte_internal(index)
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end
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def read_half(index : Int) : HalfWord
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@cycles += ACCESS_TIMING_TABLE[0][page(index)]
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read_half_internal(index)
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end
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def read_word(index : Int) : Word
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@cycles += ACCESS_TIMING_TABLE[1][page(index)]
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read_word_internal(index)
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end
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def []=(index : Int, value : Byte) : Nil
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@cycles += ACCESS_TIMING_TABLE[0][page(index)]
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write_byte_internal(index, value)
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end
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def []=(index : Int, value : HalfWord) : Nil
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@cycles += ACCESS_TIMING_TABLE[0][page(index)]
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write_half_internal(index, value)
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end
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def []=(index : Int, value : Word) : Nil
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@cycles += ACCESS_TIMING_TABLE[1][page(index)]
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write_word_internal(index, value)
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end
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def read_half_rotate(index : Int) : Word
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half = read_half(index).to_u32!
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bits = (index & 1) << 3
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half >> bits | half << (32 - bits)
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end
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# On ARM7 aka ARMv4 aka NDS7/GBA:
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# LDRH Rd,[odd] --> LDRH Rd,[odd-1] ROR 8 ;read to bit0-7 and bit24-31
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# LDRSH Rd,[odd] --> LDRSB Rd,[odd] ;sign-expand BYTE value
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def read_half_signed(index : Int) : Word
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if bit?(index, 0)
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self[index].to_i8!.to_u32!
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else
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read_half(index).to_i16!.to_u32!
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end
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end
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def read_word_rotate(index : Int) : Word
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word = read_word index
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bits = (index & 3) << 3
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word >> bits | word << (32 - bits)
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end
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@[AlwaysInline]
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private def page(index : Int) : Int
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bits(index, 24..27)
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end
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@[AlwaysInline]
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private def read_byte_internal(index : Int) : Byte
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case bits(index, 24..27)
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when 0x0 then @bios[index & 0x3FFF]
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when 0x1 then 0_u8 # todo: open bus
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@ -35,14 +101,15 @@ module GBA
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end
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end
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def read_half(index : Int) : HalfWord
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@[AlwaysInline]
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private def read_half_internal(index : Int) : HalfWord
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index &= ~1
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case bits(index, 24..27)
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when 0x0 then (@bios.to_unsafe + (index & 0x3FFF)).as(HalfWord*).value
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when 0x1 then 0_u16 # todo: open bus
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when 0x2 then (@wram_board.to_unsafe + (index & 0x3FFFF)).as(HalfWord*).value
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when 0x3 then (@wram_chip.to_unsafe + (index & 0x7FFF)).as(HalfWord*).value
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when 0x4 then read_half_slow(index)
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when 0x4 then read_half_internal_slow(index)
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when 0x5 then (@gba.ppu.pram.to_unsafe + (index & 0x3FF)).as(HalfWord*).value
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when 0x6
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address = 0x1FFFF_u32 & index
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@ -63,31 +130,15 @@ module GBA
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end
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end
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def read_half_rotate(index : Int) : Word
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half = read_half(index).to_u32!
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bits = (index & 1) << 3
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half >> bits | half << (32 - bits)
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end
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# On ARM7 aka ARMv4 aka NDS7/GBA:
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# LDRH Rd,[odd] --> LDRH Rd,[odd-1] ROR 8 ;read to bit0-7 and bit24-31
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# LDRSH Rd,[odd] --> LDRSB Rd,[odd] ;sign-expand BYTE value
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def read_half_signed(index : Int) : Word
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if bit?(index, 0)
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self[index].to_i8!.to_u32!
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else
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read_half(index).to_i16!.to_u32!
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end
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end
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def read_word(index : Int) : Word
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@[AlwaysInline]
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private def read_word_internal(index : Int) : Word
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index &= ~3
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case bits(index, 24..27)
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when 0x0 then (@bios.to_unsafe + (index & 0x3FFF)).as(Word*).value
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when 0x1 then 0_u32 # todo: open bus
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when 0x2 then (@wram_board.to_unsafe + (index & 0x3FFFF)).as(Word*).value
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when 0x3 then (@wram_chip.to_unsafe + (index & 0x7FFF)).as(Word*).value
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when 0x4 then read_word_slow(index)
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when 0x4 then read_word_internal_slow(index)
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when 0x5 then (@gba.ppu.pram.to_unsafe + (index & 0x3FF)).as(Word*).value
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when 0x6
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address = 0x1FFFF_u32 & index
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@ -108,13 +159,8 @@ module GBA
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end
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end
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def read_word_rotate(index : Int) : Word
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word = read_word index
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bits = (index & 3) << 3
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word >> bits | word << (32 - bits)
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end
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def []=(index : Int, value : Byte) : Nil
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@[AlwaysInline]
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private def write_byte_internal(index : Int, value : Byte) : Nil
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return if bits(index, 28..31) > 0
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@gba.cpu.fill_pipeline if index <= @gba.cpu.r[15] && index >= @gba.cpu.r[15] &- 4 # detect writes near pc
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case bits(index, 24..27)
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@ -131,14 +177,15 @@ module GBA
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end
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end
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def []=(index : Int, value : HalfWord) : Nil
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@[AlwaysInline]
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private def write_half_internal(index : Int, value : HalfWord) : Nil
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return if bits(index, 28..31) > 0
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index &= ~1
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@gba.cpu.fill_pipeline if index <= @gba.cpu.r[15] && index >= @gba.cpu.r[15] &- 4 # detect writes near pc
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case bits(index, 24..27)
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when 0x2 then (@wram_board.to_unsafe + (index & 0x3FFFF)).as(HalfWord*).value = value
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when 0x3 then (@wram_chip.to_unsafe + (index & 0x7FFF)).as(HalfWord*).value = value
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when 0x4 then write_half_slow(index, value)
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when 0x4 then write_half_internal_slow(index, value)
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when 0x5 then (@gba.ppu.pram.to_unsafe + (index & 0x3FF)).as(HalfWord*).value = value
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when 0x6
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address = 0x1FFFF_u32 & index
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@ -146,19 +193,20 @@ module GBA
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(@gba.ppu.vram.to_unsafe + address).as(HalfWord*).value = value
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when 0x7 then (@gba.ppu.oam.to_unsafe + (index & 0x3FF)).as(HalfWord*).value = value
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when 0xD then @gba.storage[index] = value.to_u8! if @gba.storage.eeprom? index
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when 0xE, 0xF then write_half_slow(index, value)
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when 0xE, 0xF then write_half_internal_slow(index, value)
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else log "Unmapped write: #{hex_str index.to_u32}"
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end
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end
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def []=(index : Int, value : Word) : Nil
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@[AlwaysInline]
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private def write_word_internal(index : Int, value : Word) : Nil
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return if bits(index, 28..31) > 0
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index &= ~3
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@gba.cpu.fill_pipeline if index <= @gba.cpu.r[15] && index >= @gba.cpu.r[15] &- 4 # detect writes near pc
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case bits(index, 24..27)
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when 0x2 then (@wram_board.to_unsafe + (index & 0x3FFFF)).as(Word*).value = value
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when 0x3 then (@wram_chip.to_unsafe + (index & 0x7FFF)).as(Word*).value = value
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when 0x4 then write_word_slow(index, value)
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when 0x4 then write_word_internal_slow(index, value)
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when 0x5 then (@gba.ppu.pram.to_unsafe + (index & 0x3FF)).as(Word*).value = value
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when 0x6
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address = 0x1FFFF_u32 & index
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@ -166,33 +214,37 @@ module GBA
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(@gba.ppu.vram.to_unsafe + address).as(Word*).value = value
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when 0x7 then (@gba.ppu.oam.to_unsafe + (index & 0x3FF)).as(Word*).value = value
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when 0xD then @gba.storage[index] = value.to_u8! if @gba.storage.eeprom? index
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when 0xE, 0xF then write_word_slow(index, value)
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when 0xE, 0xF then write_word_internal_slow(index, value)
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else log "Unmapped write: #{hex_str index.to_u32}"
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end
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end
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private def read_half_slow(index : Int) : HalfWord
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self[index].to_u16! |
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(self[index + 1].to_u16! << 8)
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@[AlwaysInline]
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private def read_half_internal_slow(index : Int) : HalfWord
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read_byte_internal(index).to_u16! |
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(read_byte_internal(index + 1).to_u16! << 8)
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end
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private def read_word_slow(index : Int) : Word
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self[index].to_u32! |
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(self[index + 1].to_u32! << 8) |
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(self[index + 2].to_u32! << 16) |
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(self[index + 3].to_u32! << 24)
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@[AlwaysInline]
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private def read_word_internal_slow(index : Int) : Word
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read_byte_internal(index).to_u32! |
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(read_byte_internal(index + 1).to_u32! << 8) |
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(read_byte_internal(index + 2).to_u32! << 16) |
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(read_byte_internal(index + 3).to_u32! << 24)
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end
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private def write_half_slow(index : Int, value : HalfWord) : Nil
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self[index] = value.to_u8!
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self[index + 1] = (value >> 8).to_u8!
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@[AlwaysInline]
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private def write_half_internal_slow(index : Int, value : HalfWord) : Nil
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write_byte_internal(index, value.to_u8!)
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write_byte_internal(index + 1, (value >> 8).to_u8!)
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end
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private def write_word_slow(index : Int, value : Word) : Nil
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self[index] = value.to_u8!
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self[index + 1] = (value >> 8).to_u8!
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self[index + 2] = (value >> 16).to_u8!
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self[index + 3] = (value >> 24).to_u8!
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@[AlwaysInline]
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private def write_word_internal_slow(index : Int, value : Word) : Nil
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write_byte_internal(index, value.to_u8!)
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write_byte_internal(index + 1, (value >> 8).to_u8!)
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write_byte_internal(index + 2, (value >> 16).to_u8!)
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write_byte_internal(index + 3, (value >> 24).to_u8!)
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end
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end
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end
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@ -141,7 +141,8 @@ module GBA
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else
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arm_execute instr
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end
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@gba.scheduler.tick 1
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@gba.scheduler.tick @gba.bus.cycles
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@gba.bus.cycles = 0
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else
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@gba.scheduler.fast_forward
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end
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