# Hex16.asm

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## Latest revision as of 08:34, 4 December 2010

## Contents |

# Functions Provided

Entry point | Function provided | Notes |
---|---|---|

HEX16 | Print a 16-bit hexadecimal number | This 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 ;; ;; ======================================================================== ;;