Data commit

Task/Repeat-a-string/Z80-Assembly/repeat-a-string.z80

@@ -0,0 +1,25 @@
+PrintChar equ &BB5A ;Amstrad CPC BIOS call, prints the ascii code in the accumulator to the screen.
+
+org &8000
+ld b,5                 ; repeat 5 times
+
+loop:
+call PrintImmediate
+byte "ha",0
+djnz loop
+
+ret                    ; return to basic
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+PrintImmediate:
+pop hl                 ; get the return address into HL, it's the start of the embedded string.
+call PrintString
+; inc hl               ; if your strings are null-terminated you can omit this, since a 0 equals the "NOP" instruction
+jp (hl)                ; acts as a ret, returning execution to the instruction just after the embedded string.
+
+PrintString:
+ld a,(hl)              ; read in a character from the string
+or a                   ; if your strings are null-terminated you can use this as a shortcut, otherwise use the compare instruction
+ret z                  ; exit once the terminator is reached.
+call PrintChar         ; BIOS call, all regs are preserved.
+inc hl                 ; next char
+jr PrintString         ; back to start.