;license:MIT
;(c) 2018 by 4am
;
; common assembler macros
;

; for functions that take parameters on the stack
; set (PARAM) to point to the parameters and
; move the stack pointer to the first byte after the parameters
; clobbers A,X
!macro   PARAMS_ON_STACK .bytes {
         pla
         sta   PARAM
         plx
         stx   PARAM+1
         lda   #.bytes
         clc
         adc   PARAM
         bcc   +
         inx
+        phx
         pha
}

; for functions that take parameters on the stack
; load a 16-bit value from the parameters on the stack into A (low) and Y (high)
; (assumes PARAMS_ON_STACK was used first)
!macro   LDPARAM .offset {
         ldy   #.offset+1
         lda   (PARAM),y
         pha
         dey
         lda   (PARAM),y
         ply
}

; load the address of .ptr into A (low) and Y (high)
!macro   LDADDR .ptr {
         lda   #<.ptr
         ldy   #>.ptr
}

; load a 16-bit value into A (low) and Y (high)
!macro   LDAY .ptr {
         lda   .ptr
         ldy   .ptr+1
}

; store a 16-bit value from A (low) and Y (high)
!macro   STAY .ptr {
         sta   .ptr
         sty   .ptr+1
}

; use BIT to swallow the following 1-byte opcode
!macro   HIDE_NEXT_BYTE {
         !byte $24
}

; use BIT to swallow the following 2-byte opcode
!macro   HIDE_NEXT_2_BYTES {
         !byte $2C
}