Memcmp.asm
Functions Provided
Entry point | Function provided | Notes |
---|---|---|
MEMCMP | Compare two blocks of memory | First source, second source and length fixed in ROM. |
MEMCMP.1 | First source, second source and length in registers. |
See source code below for calling convention.
Examples
(todo... please contribute!)
Notes
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 *; ;* ======================================================================== *; ;; ======================================================================== ;; ;; MEMCMP Compare Two Arrays ;; ;; MEMCMP.1 Alternate entry point ;; ;; ;; ;; AUTHOR ;; ;; Joseph Zbiciak <intvnut AT gmail.com> ;; ;; ;; ;; REVISION HISTORY ;; ;; 08-Sep-2001 Initial Revision ;; ;; ;; ;; INPUTS for MEMCMP ;; ;; R5 Pointer to invocation record, followed by return address. ;; ;; Pointer to first array 1 DECLE ;; ;; Pointer to second array 1 DECLE ;; ;; Length 1 DECLE ;; ;; ;; ;; INPUTS for MEMCMP.1 ;; ;; R5 Return address ;; ;; R4 Pointer to first array ;; ;; R1 Pointer to second array ;; ;; R0 Length ;; ;; ;; ;; OUTPUTS ;; ;; R0 Zero if all elements compared as equal, non-zero otherwise. ;; ;; R1 Last element compared against from first array. ;; ;; R4 If miscompared, points just after miscompare in 1st array, ;; ;; otherwise points to first element beyond end of array. ;; ;; R5 If miscompared, points just after miscompare in 2nd array, ;; ;; otherwise points to first element beyond end of array. ;; ;; FLAGS Result of comparison between the arrays. ;; ;; ;; ;; TECHNIQUES ;; ;; Unrolled 2x for speed. ;; ;; ;; ;; CODESIZE ;; ;; 23 words ;; ;; ;; ;; CYCLES ;; ;; If length is even: cycles = 74 + 61*floor(length / 2) ;; ;; If length is odd: cycles = 107 + 61*floor(length / 2) ;; ;; ;; ;; If calling MEMCMP.1, subtract 24 cycles from the above formulae. ;; ;; ======================================================================== ;; MEMCMP PROC MVI@ R5, R4 ; 8 First array MVI@ R5, R1 ; 8 Second array MVI@ R5, R0 ; 8 Length @@1: PSHR R5 ; 9 Alternate entry point MOVR R1, R5 ; 6 Use auto-incr pointer INCR R0 ; 6 \ Loop is unrolled 2x, so SARC R0, 1 ; 6 |-- handle the odd iteration. BNC @@odd ; 7/9 / BEQ @@done ; 7/9 Abort if length == 0. ;---- ; 65 Fallthru case ; 60 Branch to odd @@loop: MVI@ R5, R1 ; 8 \ CMP@ R4, R1 ; 8 |-- Compare one pair of words BNEQ @@done ; 7/9 / @@odd: MVI@ R5, R1 ; 8 \ CMP@ R4, R1 ; 8 |-- Compare one pair of words BNEQ @@done ; 7/9 / DECR R0 ; 6 BNEQ @@loop ; 9/7 Iterate ;---- ; 61*k - 2 @@done: PULR PC ; 11 Return, w/ result in FLAGS. ENDP ;; ======================================================================== ;; ;; End of File: memcmp.asm ;; ;; ======================================================================== ;;