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Diffstat (limited to 'include/globals.s')
| -rw-r--r-- | include/globals.s | 34 |
1 files changed, 34 insertions, 0 deletions
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 |