;license:MIT
;(c) 2018-2020 by 4am
;
; common assembler macros (6502 compatible)
;

!ifndef _MACROS_ {
         !source "src/constants.a"

; 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
         clc
         adc   #.bytes
         tay
         pla
         sta   PARAM+1
         adc   #0
         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   LD16 .ptr {
         lda   .ptr
         ldy   .ptr+1
}

; load a 16-bit value into X (low) and Y (high)
!macro   LDX16 .ptr {
         ldx   .ptr
         ldy   .ptr+1
}

; load a 16-bit immediate value into A (low) and Y (high)
!macro   LDI16 .ptr {
         lda   #<.ptr
         ldy   #>.ptr+1
}

; store a 16-bit value from A (low) and Y (high)
!macro   ST16 .ptr {
         sta   .ptr
         sty   .ptr+1
}

; store a 16-bit value from X (low) and Y (high)
!macro   STX16 .ptr {
         stx   .ptr
         sty   .ptr+1
}

; decrement a 16-bit value in A (low) and Y (high)
!macro   DEC16 {
         sec
         sbc   #1
         bcs   +
         dey
+
}

; decrement a 16-bit value in X (low) and Y (high)
; destroys A!
!macro   DEX16 {
         txa
         bne   +
         dey
+        dex
}

; increment a 16-bit value in A (low) and Y (high)
!macro   INC16 {
         clc
         adc   #1
         bne   +
         iny
+
}

; increment a 16-bit value in X (low) and Y (high)
!macro   INX16 {
         inx
         bne   +
         iny
+
}

; compare a 16-bit value in A (low) and Y (high) to an absolute address
; zeroes A!
!macro   CMP16ADDR .addr {
         eor   .addr
         bne   +
         cpy   .addr+1
+
}

; compare a 16-bit value in X (low) and Y (high) to an absolute address
!macro   CPX16ADDR .addr {
         cpx   .addr
         bne   +
         cpy   .addr+1
+
}

; compare a 16-bit value in A (low) and Y (high) to an immediate value
!macro   CMP16 .val {
         cmp   #<.val
         bne   +
         cpy   #>.val
+
}

; compare a 16-bit value in X (low) and Y (high) against zero
; requires LDX16 immediately prior, since Y comparison is implicit!
; destroys A!
!macro   CPX16_0 {
         bne   +
         txa
+
}

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

!macro   LBMI .target {
         bpl   +
         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
}

; debugging
!macro   DEBUGWAIT {
         bit   $c010
-        bit   $c000
         bpl   -
         bit   $c010
}

; 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
}

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

!macro   HGR_BYTE_TO_DHGR_BYTES {
;1GFEDCBA ->
;1GGFFEED (main) +
;1DCCBBAA (aux)
;
; in:    A = HGR byte
; out:   A = DHGR byte in mainmem
;        X = DHGR byte in auxmem
;        preserves Y
;        clobbers zero page $00,$01,$02
         sty   $02
         ldy   #$02
--       stx   $01
         ldx   #$04
-        ror   $00                   ; duplicate previous bit
         lsr                         ; fetch bit
         php
         ror   $00                   ; insert bit
         plp
         dex
         bne   -
         ldx   $00
         dey
         bne   --
         txa
         sec
         ror   $01                   ; set bit 7 explicitly on auxmem value
         ldx   $01
         ldy   $02
}

; 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   GET_MOCKINGBOARD_SPEECH { ;carry set if present
         +READ_RAM2_NO_WRITE
         lda   MockingboardStuff
         asl
         +READ_ROM_NO_WRITE
}

!macro   GET_MOCKINGBOARD_SPEECH_AND_MACHINE_STATUS { ;carry set if present
         +READ_RAM2_NO_WRITE
         lda   MockingboardStuff
         asl
         lda   MachineStatus
         +READ_ROM_NO_WRITE
}

!macro   GET_MOCKINGBOARD_SLOT { ;carry set if present
         +READ_RAM2_NO_WRITE
         lda   MockingboardStuff
         cmp   #1
         ora   #$C0
         +READ_ROM_NO_WRITE
}

!macro   GET_MOCKINGBOARD_SLOT_AND_MACHINE_STATUS { ;carry set if present
         +READ_RAM2_NO_WRITE
         lda   MockingboardStuff
         cmp   #1
         ora   #$C0
         tax
         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)
         cli                         ; enable VBL interrupts
+
}

!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 {
         inc   $101       ; (assumes LC is switched in)
         lda   #$A6
         sta   $104
         lda   #$FA
         sta   $105       ; update reset hook to reboot
         lda   #1
         sta   $FFFD
         lsr
         sta   $FFFC      ; LC reset vector fix
}

; load an external file by pathname
; LC RAM 2 MUST BE BANKED IN
; LOW BYTE OF .addr MUST BE $00
!macro   LOAD_FILE_AT .filepath, .addr {
         lda   #0
         sta   iAuxReq    ; read to main memory
         lda   #>.addr
         sta   ldrhi
         lda   iCurBlockLo
         pha
         lda   iCurBlockHi
         pha
         +LDADDR .filepath
         jsr   LoadFileDirect
         pla
         sta   iCurBlockHi
         pla
         sta   iCurBlockLo
}

_MACROS_=*
}