ccp.z80

;; ccp.z80 - Set the name of the CCP to load.
;;
;; This uses the custom BIOS function we've added to the BIOS, which was never
;; present in real CP/M.  Consider it a hook into the emulator.
;;

FCB1:                 EQU 0x5C
BDOS_ENTRY_POINT:     EQU 5


        ;;
        ;; CP/M programs start at 0x100.
        ;;
        ORG 100H

        ;; The FCB will be populated with the first argument,
        ;; if the first character of that region is a space-character
        ;; then we've got nothing specified
        ld a, (FCB1 + 1)
        cp 0x20                  ; 0x20 = 32 == SPACE
        jp z, missing_argument   ; Got a space, report the error

        ld HL, 03
        ld de, FCB1 + 1
        ld a, 31
        out (0xff), a

exit:
        LD      C,0x00
        CALL    BDOS_ENTRY_POINT

missing_argument:
        LD DE, MISSING_ARGUMENT_STR
        LD C, 0x09
        call BDOS_ENTRY_POINT
        jr exit


;;;
;;; Text output strings.
;;;
MISSING_ARGUMENT_STR:
        db "Usage: CCP [CCP|CCPZ]", 0x0a, 0x0d, "$"

END