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| author | Miquel Sabaté Solà <mikisabate@gmail.com> | 2025-03-12 22:38:12 +0100 |
|---|---|---|
| committer | Miquel Sabaté Solà <mikisabate@gmail.com> | 2025-03-12 22:38:12 +0100 |
| commit | 2627b459d9a19ce7f1b7f3a359dca3b30b66b34e (patch) | |
| tree | b03e7972050d1efac8b3103036bdad2f081c2b03 /include | |
| download | jetpac.nes-2627b459d9a19ce7f1b7f3a359dca3b30b66b34e.tar.gz jetpac.nes-2627b459d9a19ce7f1b7f3a359dca3b30b66b34e.zip | |
Start with a skeleton for the project
Signed-off-by: Miquel Sabaté Solà <mikisabate@gmail.com>
Diffstat (limited to 'include')
| -rw-r--r-- | include/apu.s | 4 | ||||
| -rw-r--r-- | include/globals.s | 34 | ||||
| -rw-r--r-- | include/oam.s | 11 | ||||
| -rw-r--r-- | include/ppu.s | 8 |
4 files changed, 57 insertions, 0 deletions
diff --git a/include/apu.s b/include/apu.s new file mode 100644 index 0000000..65d9876 --- /dev/null +++ b/include/apu.s @@ -0,0 +1,4 @@ +.scope APU + DMC = $4010 + FRAME_COUNTER = $4017 +.endscope diff --git a/include/globals.s b/include/globals.s new file mode 100644 index 0000000..d22b217 --- /dev/null +++ b/include/globals.s @@ -0,0 +1,34 @@ +;; Global variables used throughout the code base. +.scope Globals + ;;; + ;; Argument values as defined in https://github.com/mssola/style.nes. Note + ;; that these variables can also be used as temporary variables. + zp_arg0 = $00 + zp_arg1 = $01 + zp_arg2 = $02 + zp_arg3 = $03 + zp_arg4 = $04 + + ;;; + ;; Random values that can be used inside of functions for temporary values + ;; so `zp_argX` variables are not overwritten as often. + zp_tmp0 = $05 + zp_tmp1 = $06 + zp_tmp2 = $07 + zp_tmp3 = $08 + + ;;; + ;; Reserve a byte of memory for preserving indices on memory. This is needed + ;; whenever the `x` and `y` registers might not be reliable because of + ;; underlying `jsr` calls that might tamper with their values. Sometimes + ;; saving the value in memory is enough instead of playing with the stack. + zp_idx = $09 + + ;; Flags that manage the state of the game. + ;; + ;; | Bit | Short name | Meaning when set | + ;; |-----+------------+-------------------------------------------------------------| + ;; | 7 | render | Game logic is over, block main code until NMI code is over. | + ;; | 6-0 | - | Unused | + zp_flags = $20 +.endscope diff --git a/include/oam.s b/include/oam.s new file mode 100644 index 0000000..22935b2 --- /dev/null +++ b/include/oam.s @@ -0,0 +1,11 @@ +.scope OAM + ADDRESS = $2003 + DMA = $4014 +.endscope + +.macro OAM_WRITE_SPRITES + lda #$00 + sta OAM::ADDR + lda #$02 + sta OAM::DMA +.endmacro diff --git a/include/ppu.s b/include/ppu.s new file mode 100644 index 0000000..fa0df19 --- /dev/null +++ b/include/ppu.s @@ -0,0 +1,8 @@ +.scope PPU + CONTROL = $2000 + MASK = $2001 + STATUS = $2002 + SCROLL = $2005 + ADDRESS = $2006 + DATA = $2007 +.endscope |