playing-coffee/playing-coffee - Copy/roms/cpu_instrs/source/common/printing.s

99 lines
1.7 KiB
ArmAsm

; Main printing routine that checksums and
; prints to output device
; Character that does equivalent of print_newline
.define newline 10
; Prints char without updating checksum
; Preserved: BC, DE, HL
.define print_char_nocrc bss
.redefine bss bss+3
; Initializes printing. HL = print routine
init_printing:
ld a,l
ld (print_char_nocrc+1),a
ld a,h
ld (print_char_nocrc+2),a
jr show_printing
; Hides/shows further printing
; Preserved: BC, DE, HL
hide_printing:
ld a,$C9 ; RET
jr +
show_printing:
ld a,$C3 ; JP (nn)
+ ld (print_char_nocrc),a
ret
; Prints character and updates checksum UNLESS
; it's a newline.
; Preserved: AF, BC, DE, HL
print_char:
push af
cp newline
call nz,update_crc
call print_char_nocrc
pop af
ret
; Prints space. Does NOT update checksum.
; Preserved: AF, BC, DE, HL
print_space:
push af
ld a,' '
call print_char_nocrc
pop af
ret
; Advances to next line. Does NOT update checksum.
; Preserved: AF, BC, DE, HL
print_newline:
push af
ld a,newline
call print_char_nocrc
pop af
ret
; Prints immediate string
; Preserved: AF, BC, DE, HL
.macro print_str ; string,string2
push hl
call print_str_
.byte \1
.if NARGS > 1
.byte \2
.endif
.if NARGS > 2
.byte \3
.endif
.byte 0
pop hl
.endm
print_str_:
pop hl
call print_str_hl
jp hl
; Prints zero-terminated string pointed to by HL.
; On return, HL points to byte AFTER zero terminator.
; Preserved: AF, BC, DE
print_str_hl:
push af
jr +
- call print_char
+ ldi a,(hl)
or a
jr nz,-
pop af
ret