Hex16.asm

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Contents

Functions Provided

Entry pointFunction providedNotes
HEX16Print a 16-bit hexadecimal numberThis file does not coexist with hexdisp.asm.



See source code below for calling convention.

Examples

(todo... please contribute!)

Notes

This file does not coexist with hexdisp.asm. If you need more general hexadecimal number display routines, use that file, not this one.

Source Code

;* ======================================================================== *;
;*  These routines are placed into the public domain by their author.  All  *;
;*  copyright rights are hereby relinquished on the routines and data in    *;
;*  this file.  -- Joseph Zbiciak, 2008                                     *;
;* ======================================================================== *;

;;==========================================================================;;
;;  NOTE:  IF YOU NEED ANY OF HEX4, HEX8, HEX12, HEX4M, HEX8M or HEX12M,    ;;
;;  DO NOT USE THIS FILE.  USE "hexdisp.asm" INSTEAD.  THIS FILE AND THAT   ;;
;;  ONE CANNOT BE USED TOGETHER.                                            ;;
;;==========================================================================;;

;; ======================================================================== ;;
;;  HEX16                                                                   ;;
;;      Display a 4-digit hex number on the screen                          ;;
;;                                                                          ;;
;;  INPUTS:                                                                 ;;
;;      R0 -- Hex number                                                    ;;
;;      R1 -- Color mask / screen format word                               ;;
;;      R4 -- Screen offset                                                 ;;
;;                                                                          ;;
;;  OUTPUTS:                                                                ;;
;;      R0 -- rotated left by 3                                             ;;
;;      R1 -- unmodified                                                    ;;
;;      R2 -- trashed                                                       ;;
;;      R3 -- zeroed                                                        ;;
;;      R4 -- points just to right of string                                ;;
;; ======================================================================== ;;
HEX16           PROC
        ; Rotate R0 left by 3, so that our digit will be in the correct
        ; position within the screen format word.
        MOVR    R0,     R3
        SLLC    R3,     2
        RLC     R0,     2       ; First, rotate by two bits...
        SLLC    R3,     1
        RLC     R0,     1       ; ... and then by one more.

        MVII    #4,     R3      ; Iterate through four digits.
@@loop:
        ; Rotate R0 left by 4, so that we can cycle through each digit
        ; one at a time.
        MOVR    R0,     R2
        SLLC    R2,     2
        RLC     R0,     2       ; First, rotate by two bits...
        SLLC    R2,     2
        RLC     R0,     2       ; ... and then by two more.

        ; Mask out a single hex digit
        MOVR    R0,     R2
        ANDI    #$78,   R2

        ; Is it A..F?  If so, add an offset so that the correct ASCII
        ; value is selected.  Otherwise do nothing special.
        CMPI    #$50,   R2      ; $50 is $A shifted left by 3.
        BLT     @@digit
        ADDI    #$38,   R2      ; If the digit >= A, add 7 << 3.
@@digit:
        ADDI    #$80,   R2      ; Generate proper GROM index.
        XORR    R1,     R2      ; Merge in the screen format word
        MVO@    R2,     R4      ; Display the digit to the screen.

        DECR    R3              ; Iterate three more times.
        BNE     @@loop

        JR      R5              ; Done!  Return.
        ENDP

;; ======================================================================== ;;
;;  End of File:  hex16.asm                                                 ;;
;; ======================================================================== ;;
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