4cade/src/macros.a

;license:MIT
;(c) 2018-9 by 4am
;
; common assembler macros (6502 compatible)
;

; 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,Y
!macro   PARAMS_ON_STACK .bytes {
         pla
         sta   PARAM
         pla
         tax
         stx   PARAM+1
         lda   #.bytes
         clc
         adc   PARAM
         tay
         bcc   +
         inx
+        txa
         pha
         tya
         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
         lda   (PARAM),y
         pha
         iny
         lda   (PARAM),y
         tay
         pla
}

; 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)
; then store it as new source
; (assumes PARAMS_ON_STACK was used first)
!macro   LDPARAMPTR .offset,.dest {
         ldy   #.offset
         lda   (PARAM),y
         sta   .dest
         iny
         lda   (PARAM),y
         sta   .dest+1
}

; 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
}

!macro   LBPL .target {
         bmi   +
         jmp   .target
+
}

!macro   LBNE .target {
         beq   +
         jmp   .target
+
}

!macro   LBCS .target {
         bcc   +
         jmp   .target
+
}

; 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
}

; various language card configurations
!macro   READ_RAM1_NO_WRITE {
         bit   $C088
}

!macro   READ_RAM1_WRITE_RAM1 {
         bit   $C08B
         bit   $C08B
}

!macro   READ_RAM2_NO_WRITE {
         bit   $C080
}

!macro   READ_RAM2_WRITE_RAM2 {
         bit   $C083
         bit   $C083
}

!macro   READ_ROM_WRITE_RAM1 {
         bit   $C089
         bit   $C089
}

!macro   READ_ROM_WRITE_RAM2 {
         bit   $C081
         bit   $C081
}

!macro   READ_ROM_NO_WRITE {
         bit   $C082
}

!macro   LOW_ASCII_TO_LOWER {
         cmp   #$41
         bcc   +
         cmp   #$5B
         bcs   +
         ora   #$20
+
}

; requires setting zpCharMask in zero page to #$FF or #$DF before use
!macro   FORCE_UPPERCASE_IF_REQUIRED {
         cmp   #$E1
         bcc   +
         and   zpCharMask
+
}

; these are mostly for prelaunchers -- code in the main program should keep track of which bank is active to minimize code size
!macro   ENABLE_ACCEL {
         +READ_RAM2_NO_WRITE
         jsr   EnableAccelerator
         +READ_ROM_NO_WRITE
}

!macro   DISABLE_ACCEL {
         +READ_RAM2_NO_WRITE
         jsr   DisableAccelerator
         +READ_ROM_NO_WRITE
}

!macro   GET_MACHINE_STATUS {
         +READ_RAM2_NO_WRITE
         lda   MachineStatus
         +READ_ROM_NO_WRITE
}

!macro   USES_TEXT_PAGE_2 {
         lda   ROM_MACHINEID
         cmp   #$06
         bne   +
         sec
         jsr   $FE1F                 ; check for IIgs
         bcs   +
         jsr   ROM_TEXT2COPY         ; set alternate display mode on IIgs (required for some games)
+
}

!macro   RESET_VECTOR .addr {
         lda   #<.addr
         sta   $3F2
         lda   #>.addr
         sta   $3F3
         eor   #$A5
         sta   $3F4
}

; for games that clobber $100-$105, the prelaunch code constructs a new reset vector
; somewhere else and sets its
!macro   NEW_RESET_VECTOR .addr {
         lda   #$2C
         sta   .addr
         lda   #$88
         sta   .addr+1
         lda   #$C0
         sta   .addr+2
         lda   #$6C       ; JMP ($FFFC) points to 'Reenter'
         sta   .addr+3
         lda   #$FC
         sta   .addr+4
         lda   #$FF
         sta   .addr+5
         +RESET_VECTOR .addr
}

; for 64k games on ][+ which either hang or restart
; updates reset hook to reboot on ctrl-reset
!macro   LC_REBOOT {
         lda   #$82       ; (assumes LC is switched in)
         sta   $101
         lda   #$A6
         sta   $104
         lda   #$FA
         sta   $105       ; update reset hook to reboot
         lda   #0
         sta   $FFFC
         lda   #1
         sta   $FFFD      ; LC reset vector fix
}