a2console.asm

; Apple ][ Dead Test RAM Diagnostic ROM
; Copyright (C) 2023  David Giller

; This program is free software; you can redistribute it and/or modify
; it under the terms of the GNU General Public License as published by
; the Free Software Foundation; either version 2 of the License, or
; (at your option) any later version.

; This program is distributed in the hope that it will be useful,
; but WITHOUT ANY WARRANTY; without even the implied warranty of
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
; GNU General Public License for more details.

; You should have received a copy of the GNU General Public License along
; with this program; if not, write to the Free Software Foundation, Inc.,
; 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

.zeropage
	con_loc:	.res 2
	con_str:	.res 2
	con_xsave:	.res 1
	con_ysave:	.res 1
	con_asave:	.res 1
.code



; .proc con_put
; 		rts
; .endproc



; ; setup: con_loc is destination location, con_str is the string to write
; .proc	_con_put_sz
; 	put:
; 		lda (con_str),Y	; fetch char
; 		beq end			; finish on zero byte
; 		sta (con_loc),Y	; emit the string
; 		inc con_loc		; increment location
; 		bne nextchar
; 		inc con_loc+1
; 	nextchar:
; 		inc	con_str		; increment pointer
; 		bne put			; skip if no carry
; 		inc con_str+1	; now con_str points to start of the string
; 		jmp put
; 	end:
; 		rts
; .endproc

; print a string with args immediately embedded after the calling function
; first screen location, then the string itself, zero-terminated
; adapted from Don Lancaster's "Assembly Cookbook for the Apple II/IIe"
.proc	con_puts_embedded
		stx con_xsave
		sty con_ysave
		sta con_asave

		pla				; fetch address of argument (minus one)
		sta con_str
		pla
		sta con_str+1

		ldy	#$00

		inc	con_str		; increment pointer
		bne :+			; skip if no carry
		inc con_str+1	; now con_str points to the screen location lo byte
	:	lda (con_str),Y	; fetch lo byte
		sta con_loc		; store new screen location
		inc	con_str		; increment pointer
		bne :+			; skip if no carry
		inc con_str+1	; now con_str points to the screen location hi byte
	:	lda (con_str),Y	; fetch hi byte
		sta con_loc+1

		; jsr _con_put_sz::nextchar
	nextchar:
		inc	con_str		; increment pointer
		bne :+			; skip if no carry
		inc con_str+1	; now con_str points to start of the string
	:	lda (con_str),Y	; fetch char
		beq end			; finish on zero byte
		sta (con_loc),Y	; emit the string
		inc con_loc		; increment location
		bne :+
		inc con_loc+1
	:	clc
		bcc nextchar	; branch (always) to next char

	end:
		lda con_str+1	; fix up the stack for return
		pha
		lda con_str
		pha
		lda con_asave	; restore regs
		lda con_ysave
		lda con_xsave
		rts
.endproc

; print value in A to current screen location
.proc	con_put_hex
		sta con_asave		; save the value for reuse

		LSR					; shift the high nybble into the low
		LSR
		LSR
		LSR
		TAY					; use it as an index
		LDA hex_tbl,Y		; into the hex table
		LDY #0
		STA (con_loc),Y		; store the low nybble

		lda con_asave		; get another copy
		AND #$0F			; get low nybble
		TAY					; use it as an index
		LDA hex_tbl,Y		; into the hex table
		LDY #1
		STA (con_loc),Y		; store the low nybble
		RTS
.endproc

.proc con_cls
		inline_cls
		rts
.endproc

; params:
; A = column
; Y = row
; doesn't touch X
.proc con_goto
		pha					; save A (column) on stack
		tya
		asl					; multiply Y by 2
		tay
		lda line_to_base,Y	; get the base address (lo)
		sta con_loc
		lda line_to_base+1,Y; get the base address (hi)
		sta con_loc+1
		pla					; get the column back
		clc					; add the column to the base
		adc con_loc
		sta	con_loc			; store back to the base address
		rts					; we don't need to carry, as no valid line crosses a page
.endproc

line_to_base: .word $400,$480,$500,$580,$600,$680,$700,$780
			  .word $428,$4A8,$528,$5A8,$628,$6A8,$728,$7A8
			  .word $450,$4D0,$550,$5D0,$650,$6D0,$750,$7D0
line_to_base_end = *