Ca65 macros

.feature leading_dot_in_identifiers
.macpack generic
.macpack longbranch

; Meant to be an easy replacement for .repeat and .endrepeat
; when you're trying to save space. Uses a zeropage memory location
; instead of a register as a loop counter so as not to disturb any
; registers.
; Times - Number of times to loop ( may be a memory location )
; Free  - Free zeropage memory location to use
.macro .dj_loop Times, Free
  .scope
    DJ_Counter = Free
    lda Times
    sta Free
DJ_Label:
.endmacro
.macro .end_djl
  NextIndex:
    dec DJ_Counter
    jne DJ_Label
  .endscope
.endmacro


; Imitation of z80's djnz opcode.
; Can be on A, X, Y, or a zeropage memory location
; Label - Label to jump to
; Reg   - Counter register to use: A,X,Y or memory location
.macro djnz Label, Reg
  .if (.match({Reg}, a))
    sub #1
  .elseif (.match({Reg}, x))
    dex
  .elseif (.match({Reg}, y))
    dey
  .else
    dec var
  .endif
  bne Label
.endmacro


; Working with X,Y is much more fun than working with PPU addresses
; give it an X and Y position, as well as a nametable number (0-3),
; and if you want to save the address to a 16-bit zeropage address
; ( big endian ) you can give an additional argument.
; NT - Nametable number (0-3)
; PX - X position in tiles
; PY - Y position in tiles
; Var - Variable to store address in (optional)
.macro PositionXY NT, PX, PY, Var
	.scope
		t0 = $2000 + (NT * 1024)	; Nametable data starts at $2000
		t1 = PX                 ; and each nametable is 1024 bytes in size
		t2 = PY * 32			; Nametable rows are 32 bytes large
		t3 = t0 + t1 + t2
        .ifblank Var
          lda #>t3
          sta $2006
          lda #<t3
          sta $2006
        .else
          lda #>t3
          sta Var+0
          lda #<t3
          sta Var+1
        .endif
	.endscope
.endmacro