gbdk-2020 | GameBoy Development Kit |
| download: https://git.y1.nz/archives/gbdk.tar.gz | |
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commit 02046e14c91246d6cd993797984eec17068a49f9 parent f567c7970893b4ee6819624e1cc3c8f9488d12ca Author: Michel Iwaniec <46843052+michel-iwaniec@users.noreply.github.com> Date: Wed, 7 Feb 2024 14:39:07 +0000 Merge pull request #626 from michel-iwaniec/nes_transfer_buffer_optimization_followup NES: Transfer buffer optimization follow-up fix / rename Diffstat:
| M | gbdk-lib/libc/targets/mos6502/nes/vram_transfer_buffer.s | 47 | +++++++++++++++++++++++++++++------------------ |
1 file changed, 29 insertions(+), 18 deletions(-)
diff --git a/gbdk-lib/libc/targets/mos6502/nes/vram_transfer_buffer.s b/gbdk-lib/libc/targets/mos6502/nes/vram_transfer_buffer.s @@ -16,7 +16,7 @@ ; 4: ...N data bytes... ; VRAM_HDR_SIZEOF = 4 -VRAM_HDR_LENGTH = 0 +VRAM_HDR_JMPADDR = 0 VRAM_HDR_DIRECTION = 1 VRAM_HDR_PPUHI = 2 VRAM_HDR_PPULO = 3 @@ -39,6 +39,18 @@ VRAM_MAX_STRIPE_SIZE = VRAM_HDR_SIZEOF + VRAM_MAX_BYTES ror *__vram_transfer_buffer_valid .endm +; +; Converts data length into JMP address for unrolled loop +; +; jmp addr = 128-4*num_bytes + 1 = NOT(4*num_bytes)+1+128 + 1 = NOT(4*num_bytes)+130 +; +.macro LENGTH_TO_JMPADDR + asl + asl + eor #0xFF + adc #130 +.endm + .area GBDKOVR (PAG, OVR) _set_vram_byte_PARM_2:: .ds 1 @@ -147,13 +159,9 @@ __vram_transfer_buffer_pos_old:: .ds 1 sbc *__vram_transfer_buffer_pos_old sbc #VRAM_HDR_SIZEOF pha - ; branchaddr = 128-4*num_bytes + 1 = NOT(4*num_bytes)+1+128 + 1 = NOT(4*num_bytes)+130 - asl - asl - eor #0xFF - adc #130 + LENGTH_TO_JMPADDR ldy *__vram_transfer_buffer_pos_old - sta __vram_transfer_buffer+VRAM_HDR_LENGTH,y + sta __vram_transfer_buffer+VRAM_HDR_JMPADDR,y pla eor #0xFF sec @@ -235,11 +243,12 @@ _set_vram_byte:: lda __vram_transfer_buffer+VRAM_HDR_PPUHI,x cmp *ppu_addr+1 bne .ppu_stripe_append_failed - lda __vram_transfer_buffer+VRAM_HDR_LENGTH,x - cmp #VRAM_MAX_BYTES + ; Don't handle appending if old size has reached VRAM_MAX_BYTES + lda __vram_transfer_buffer+VRAM_HDR_JMPADDR,x + cmp #(128-4*VRAM_MAX_BYTES + 1) beq .ppu_stripe_append_failed ; if last stripe only contains a single byte, branch to go-either-direction routine - cmp #1 + cmp #(128-4*1 + 1) beq .ppu_stripe_append_second_byte ; Test for horizontal stripe lda __vram_transfer_buffer+VRAM_HDR_DIRECTION,x @@ -248,7 +257,8 @@ _set_vram_byte:: lda *ppu_addr sec sbc __vram_transfer_buffer+VRAM_HDR_PPULO,x - cmp __vram_transfer_buffer+VRAM_HDR_LENGTH,x + LENGTH_TO_JMPADDR + cmp __vram_transfer_buffer+VRAM_HDR_JMPADDR,x beq 0$ jmp .ppu_stripe_append_failed 0$: @@ -264,7 +274,8 @@ _set_vram_byte:: lsr sec sbc __vram_transfer_buffer+VRAM_HDR_PPULO,x - cmp __vram_transfer_buffer+VRAM_HDR_LENGTH,x + LENGTH_TO_JMPADDR + cmp __vram_transfer_buffer+VRAM_HDR_JMPADDR,x bne .ppu_stripe_append_failed ; Append 1 byte jmp .ppu_stripe_append_1byte @@ -277,9 +288,9 @@ _set_vram_byte:: lda #0 sta __vram_transfer_buffer+VRAM_HDR_DIRECTION,y sta __vram_transfer_buffer+VRAM_HDR_SIZEOF+1,y - ; Write length + ; Write jmp addr lda #(128-4*1 + 1) - sta __vram_transfer_buffer+VRAM_HDR_LENGTH,y + sta __vram_transfer_buffer+VRAM_HDR_JMPADDR,y ; Write address lda *ppu_addr+1 sta __vram_transfer_buffer+VRAM_HDR_PPUHI,y @@ -327,10 +338,10 @@ _set_vram_byte:: .ppu_stripe_append_1byte: ; Append 1 byte - dec __vram_transfer_buffer+VRAM_HDR_LENGTH,x - dec __vram_transfer_buffer+VRAM_HDR_LENGTH,x - dec __vram_transfer_buffer+VRAM_HDR_LENGTH,x - dec __vram_transfer_buffer+VRAM_HDR_LENGTH,x + dec __vram_transfer_buffer+VRAM_HDR_JMPADDR,x + dec __vram_transfer_buffer+VRAM_HDR_JMPADDR,x + dec __vram_transfer_buffer+VRAM_HDR_JMPADDR,x + dec __vram_transfer_buffer+VRAM_HDR_JMPADDR,x lda *_set_vram_byte_PARM_2 ldx *__vram_transfer_buffer_pos_w sta __vram_transfer_buffer,x
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