view release on metacpan or  search on metacpan

t/data/zx48.asm  view on Meta::CPAN

                                ; 'Nonsense in BASIC'

; -------------------
; CO-TEMP-3
; -------------------
; -> this routine evaluates and outputs a colour control and parameter.
; It is called from above and also from PR-ITEM-3 to handle a single embedded
; print item e.g. PRINT PAPER 6; "Hi". In the latter case, the looping for
; multiple items is within the PR-ITEM routine.
; It is quite permissible to send these to any stream.

;; CO-TEMP-3
L21F2:  CP      $D9             ; is it 'INK' ?
        RET     C               ; return if less.

        CP      $DF             ; compare with 'OUT'
        CCF                     ; Complement Carry Flag
        RET     C               ; return if greater than 'OVER', $DE.

        PUSH    AF              ; save the colour token.

        RST     20H             ; address NEXT-CHAR
        POP     AF              ; restore token and continue.

; -> this entry point used by CLASS-07. e.g. the command PAPER 6.

;; CO-TEMP-4
L21FC:  SUB     $C9             ; reduce to control character $10 (INK)
                                ; thru $15 (OVER).
        PUSH    AF              ; save control.
        CALL    L1C82           ; routine EXPT-1NUM stacks addressed
                                ; parameter on calculator stack.
        POP     AF              ; restore control.
        AND     A               ; clear carry

        CALL    L1FC3           ; routine UNSTACK-Z returns if checking syntax.

        PUSH    AF              ; save again
        CALL    L1E94           ; routine FIND-INT1 fetches parameter to A.
        LD      D,A             ; transfer now to D
        POP     AF              ; restore control.

        RST     10H             ; PRINT-A outputs the control to current
                                ; channel.
        LD      A,D             ; transfer parameter to A.

        RST     10H             ; PRINT-A outputs parameter.
        RET                     ; return. ->

; -------------------------------------------------------------------------
;
;         {fl}{br}{   paper   }{  ink    }    The temporary colour attributes
;          ___ ___ ___ ___ ___ ___ ___ ___    system variable.
; ATTR_T  |   |   |   |   |   |   |   |   |
;         |   |   |   |   |   |   |   |   |
; 23695   |___|___|___|___|___|___|___|___|
;           7   6   5   4   3   2   1   0
;
;
;         {fl}{br}{   paper   }{  ink    }    The temporary mask used for
;          ___ ___ ___ ___ ___ ___ ___ ___    transparent colours. Any bit
; MASK_T  |   |   |   |   |   |   |   |   |   that is 1 shows that the
;         |   |   |   |   |   |   |   |   |   corresponding attribute is
; 23696   |___|___|___|___|___|___|___|___|   taken not from ATTR-T but from
;           7   6   5   4   3   2   1   0     what is already on the screen.
;
;
;         {paper9 }{ ink9 }{ inv1 }{ over1}   The print flags. Even bits are
;          ___ ___ ___ ___ ___ ___ ___ ___    temporary flags. The odd bits
; P_FLAG  |   |   |   |   |   |   |   |   |   are the permanent flags.
;         | p | t | p | t | p | t | p | t |
; 23697   |___|___|___|___|___|___|___|___|
;           7   6   5   4   3   2   1   0
;
; -----------------------------------------------------------------------

; ------------------------------------
;  The colour system variable handler.
; ------------------------------------
; This is an exit branch from PO-1-OPER, PO-2-OPER
; A holds control $10 (INK) to $15 (OVER)
; D holds parameter 0-9 for ink/paper 0,1 or 8 for bright/flash,
; 0 or 1 for over/inverse.

;; CO-TEMP-5
L2211:  SUB     $11             ; reduce range $FF-$04
        ADC     A,$00           ; add in carry if INK
        JR      Z,L2234         ; forward to CO-TEMP-7 with INK and PAPER.

        SUB     $02             ; reduce range $FF-$02
        ADC     A,$00           ; add carry if FLASH
        JR      Z,L2273         ; forward to CO-TEMP-C with FLASH and BRIGHT.

        CP      $01             ; is it 'INVERSE' ?
        LD      A,D             ; fetch parameter for INVERSE/OVER
        LD      B,$01           ; prepare OVER mask setting bit 0.
        JR      NZ,L2228        ; forward to CO-TEMP-6 if OVER

        RLCA                    ; shift bit 0
        RLCA                    ; to bit 2
        LD      B,$04           ; set bit 2 of mask for inverse.

;; CO-TEMP-6
L2228:  LD      C,A             ; save the A
        LD      A,D             ; re-fetch parameter
        CP      $02             ; is it less than 2
        JR      NC,L2244        ; to REPORT-K if not 0 or 1.
                                ; 'Invalid colour'.

        LD      A,C             ; restore A
        LD      HL,$5C91        ; address system variable P_FLAG
        JR      L226C           ; forward to exit via routine CO-CHANGE

; ---

; the branch was here with INK/PAPER and carry set for INK.

;; CO-TEMP-7
L2234:  LD      A,D             ; fetch parameter
        LD      B,$07           ; set ink mask 00000111
        JR      C,L223E         ; forward to CO-TEMP-8 with INK