diff options
Diffstat (limited to 'src/1.s')
| -rw-r--r-- | src/1.s | 176 |
1 files changed, 157 insertions, 19 deletions
@@ -2,13 +2,8 @@ ;; Day 1 https://adventofcode.com/2023/day/1 ;; ;; This program then iterates over the array on `data` and computes the value on -;; each row, then accumulating it into a sum variable. This variable is stored -;; as a 16-bit number on $08-$09. In order to see the actual result, in FCEUX, -;; for example, you need to go to `Tools -> RAM Watch`, and set a watch on -;; address $08 which is unsigned and 2-bytes long. This will show you the end -;; result after a couple of seconds (yes, it's a big ass computation for poor -;; old NES, and it's quite fast considering that we are not rendering anything -;; on screen!). The result must be: `54953`. +;; each row, then accumulating it into a sum variable. The end result will be +;; printed to the screen, which must be `54953`. ;; Luckily for us, good ol' NROM can fit the data set for this exercise :D .segment "HEADER" @@ -24,6 +19,8 @@ .addr nmi, reset, irq .segment "CHARS" + .incbin "../assets/alphanum.chr" + .segment "STARTUP" .segment "CODE" @@ -32,6 +29,7 @@ .include "../include/ppu.s" .include "../include/reset.s" .include "../include/globals.s" +.include "../vendor/bcd16.s" ;; "Variables" used by this program. .scope Vars @@ -80,23 +78,24 @@ ;; The main function will be called at the end of the `reset` vector as defined ;; in `include/reset.s`. .proc main - cli - - lda #%10010000 - sta PPU::CONTROL - lda #%00011110 - sta PPU::MASK - - ;; Initialize variables being used for this program. + ;; Initialize palettes and variables being used for this program. + jsr init_palettes jsr Vars::init ;; This program uses two flags: - ;; - 7 (`render`): whether NMI-code can render stuff on screen. Unused but - ;; reserved out of habit. + ;; - 7 (`render`): whether NMI-code can render stuff on screen. ;; - 6 (`done`): whether the computation has been done. - lda #0 + ;; Note that we are setting the render flag so the initial message is + ;; shown. + lda #%10000000 sta Globals::m_flags + cli + + lda #%10010000 + sta PPU::CONTROL + lda #%00011110 + sta PPU::MASK @loop: jsr compute_next jmp @loop @@ -187,6 +186,17 @@ lda #%01000000 ora Globals::m_flags sta Globals::m_flags + + ;; Now that we are done, convert the 16-bit number into separate bytes so it + ;; can be rendered on NMI-code. + lda Vars::m_sum + 1 + sta bcdNum + lda Vars::m_sum + sta bcdNum + 1 + jsr bcdConvert + + ;; Because of the previous, we can set the `render` flag again. + SET_RENDER_FLAG @end: rts .endproc @@ -221,8 +231,136 @@ rts .endproc -;; Unused. +;; init_palettes copies all the palettes into the proper PPU address. +.proc init_palettes + PPU_ADDR $3F00 + + ldx #0 +@load_palettes_loop: + lda palettes, x + sta PPU::DATA + inx + cpx #$20 + bne @load_palettes_loop + rts +palettes: + ;; Background (only first one used) + .byte $0F, $30, $10, $00 + .byte $0F, $00, $00, $00 + .byte $0F, $00, $00, $00 + .byte $0F, $00, $00, $00 + + ;; Foreground (unused) + .byte $0F, $00, $00, $00 + .byte $0F, $00, $00, $00 + .byte $0F, $00, $00, $00 + .byte $0F, $00, $00, $00 +.endproc + +;; Non-Maskable Interrupts handler. nmi: + bit PPU::STATUS + + ;; Skip rendering if the `render` flag is not set. + bit Globals::m_flags + bpl @nmi_next + + ;; Backup registers. + pha + txa + pha + tya + pha + + ;; If the result is not there yet, then we just print an initial message. + ;; Otherwise print the given result. + bit Globals::m_flags + bvs :+ + jsr print_message + jmp :++ +: + jsr print_result +: + + ;; Reset the scroll. + bit PPU::STATUS + lda #$00 + sta PPU::SCROLL + sta PPU::SCROLL + + ;; And unset the render flag so the `main` code is unblocked. + UNSET_RENDER_FLAG + + ;; Restore registers. + pla + tay + pla + tax + pla +@nmi_next: + rti + +;; Simply print "Please wait..." to the screen. +.proc print_message + WRITE_PPU_DATA $2129, $2A + WRITE_PPU_DATA $212A, $26 + WRITE_PPU_DATA $212B, $1F + WRITE_PPU_DATA $212C, $1B + WRITE_PPU_DATA $212D, $2D + WRITE_PPU_DATA $212E, $1F + + WRITE_PPU_DATA $2130, $31 + WRITE_PPU_DATA $2131, $1B + WRITE_PPU_DATA $2132, $23 + WRITE_PPU_DATA $2133, $2E + WRITE_PPU_DATA $2134, $36 + WRITE_PPU_DATA $2135, $36 + WRITE_PPU_DATA $2136, $36 + + rts +.endproc + +;; Print the result on screen. This assumes that `bcdResult` already contains +;; the proper data. +.proc print_result + ;; Clear tiles that were written by `print_message` and that are not re-used + ;; here. + WRITE_PPU_DATA $2129, $00 + WRITE_PPU_DATA $212A, $00 + WRITE_PPU_DATA $212B, $00 + WRITE_PPU_DATA $212C, $00 + WRITE_PPU_DATA $212D, $00 + WRITE_PPU_DATA $2133, $00 + WRITE_PPU_DATA $2134, $00 + WRITE_PPU_DATA $2135, $00 + WRITE_PPU_DATA $2136, $00 + + ;; And loop so PPU::ADDRESS $2E21-$2E32 has the data as stored on bcdResult, + ;; which is the binary to decimal conversion result when the final + ;; computation was done. + ldx #4 + ldy #$2E +@loop: + ;; PPU address. + bit PPU::STATUS + lda #$21 + sta PPU::ADDRESS + sty PPU::ADDRESS + + ;; PPU data. + lda bcdResult, x + clc + adc #$10 + sta PPU::DATA + dex + iny + cpy #$33 + bne @loop + + rts +.endproc + +;; Unused. irq: rti |