Posted to PICList Mon, 3 Jul 2000 00:04:54 -0400
LIST P = 16C54, n = 66 ; ;******************************************************************* ; Double Precision Multiplication ; ; ( Optimized for Speed : straight Line Code ) ; ;*******************************************************************; ; Multiplication : ACCb(16 bits) * ACCa(16 bits) -> ACCb,ACCc (32bits ) ; (a) Load the 1st operand in location ACCaLO & ACCaHI ( 16bits ) ; (b) Load the 2nd operand in location ACCbLO & ACCbHI ( 16bits ) ; (c) CALL D_mpy ; (d) The 32 bit result is in location (ACCbHI,ACCbLO,ACCcHI,ACCcLO ) ; ; Performance : ; Program Memory : 240 ; Clock Cycles : 233 (282) ; ; Note : The above timing is the worst case timing, when the ; register ACCb = FFFF. The speed may be improved if ; the register ACCb contains a number ( out of the two ; numbers ) with less number of 1s. ; ; The performance specs are for Unsigned arithmetic (i.e, ; with "SIGNED equ FALSE "). ; ; Program: DBL_MPYF.ASM ; Revision Date: ; 1-13-97 Compatibility with MPASMWIN 1.40 ; ;*******************************************************************; ; ACCaLO equ 10 ACCaHI equ 11 ACCbLO equ 12 ACCbHI equ 13 ACCcLO equ 14 ACCcHI equ 15 ACCdLO equ 16 ACCdHI equ 17 temp equ 18 sign equ 19 ;---------------------- ; Inserted by RAVI PAILOOR loopctr equ 1A ;---------------------- ; include "p16c5x.inc" PIC54 equ 1FFH ; Define Reset Vector TRUE equ 1 FALSE equ 0 org 0 ;******************************************************************* SIGNED equ FALSE ; Set This To 'TRUE' if the routines ; ; for Multiplication & Division needs ; ; to be assembled as Signed Integer ; ; Routines. If 'FALSE' the above two ; ; routines ( D_mpy & D_div ) use ; ; unsigned arithmetic. ;******************************************************************* ; multiplication macro ; mulMac MACRO LOCAL NO_ADD ; rrf ACCdHI, F ;rotate d right rrf ACCdLO, F btfss STATUS,C ;need to add? goto NO_ADD ; no addition necessary movf ACCaLO,W ; Addition ( ACCb + ACCa -> ACCb ) addwf ACCbLO, F ;add lsb btfsc STATUS,C ;add in carry incf ACCbHI, F movf ACCaHI,W addwf ACCbHI, F ;add msb NO_ADD rrf ACCbHI, F rrf ACCbLO, F rrf ACCcHI, F rrf ACCcLO, F ; ENDM ; ;*******************************************************************; ; Double Precision Multiply ( 16x16 -> 32 ) ; ( ACCb*ACCa -> ACCb,ACCc ) : 32 bit output with high word ; in ACCb ( ACCbHI,ACCbLO ) and low word in ACCc ( ACCcHI,ACCcLO ). ; D_mpyF ;results in ACCb(16 msb's) and ACCc(16 lsb's) ; IF SIGNED CALL S_SIGN ENDIF ; call setup ; ; use the mulMac macro 16 times ; ;---------------------- ; inserted by RAVI PAILOOR movlw .16 movwf loopctr ;---------------------- loop mulMac ;---------------------- ; inserted by RAVI PAILOOR decfsz loopctr,f goto loop ;---------------------- ORIGNAL ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac ; mulMac IF SIGNED btfss sign,MSB retlw 0 comf ACCcLO ; negate ACCa ( -ACCa -> ACCa ) incf ACCcLO btfsc STATUS,Z decf ACCcHI comf ACCcHI btfsc STATUS,Z neg_B comf ACCbLO ; negate ACCb incf ACCbLO btfsc STATUS,Z decf ACCbHI comf ACCbHI retlw 0 ELSE retlw 0 ENDIF ; ;******************************************************************* ; setup movlw .16 ; for 16 shifts movwf temp movf ACCbHI,W ;move ACCb to ACCd movwf ACCdHI movf ACCbLO,W movwf ACCdLO clrf ACCbHI clrf ACCbLO retlw 0 ; ;******************************************************************* ; neg_A comf ACCaLO, F ; negate ACCa ( -ACCa -> ACCa ) incf ACCaLO, F btfsc STATUS,Z decf ACCaHI, F comf ACCaHI, F retlw 0 ; ;******************************************************************* ; Assemble this section only if Signed Arithmetic Needed ; IF SIGNED ; S_SIGN movf ACCaHI,W xorwf ACCbHI,W movwf sign btfss ACCbHI,MSB ; if MSB set go & negate ACCb goto chek_A ; comf ACCbLO ; negate ACCb incf ACCbLO btfsc STATUS,Z decf ACCbHI comf ACCbHI ; chek_A btfss ACCaHI,MSB ; if MSB set go & negate ACCa retlw 0 goto neg_A ; ENDIF ; ;******************************************************************* ; Test Program ;******************************************************************* ; Load constant values to ACCa & ACCb for testing ; loadAB movlw 1 movwf ACCaHI movlw 0FF ; loads ACCa = 01FF movwf ACCaLO ; movlw 07F movwf ACCbHI movlw 0FF ; loads ACCb = 7FFF movwf ACCbLO retlw 0 ; main nop ; call loadAB ; result of multiplying ACCb*ACCa->(ACCb,ACCc) call D_mpyF ; Here (ACCb,ACCc) = 00FF 7E01 ; self goto self ; org PIC54 goto main END ;**************************************************************** -- Ravi Pailoor
Comments:
file: /Techref/microchip/math/mul/16x16rp.htm, 6KB, , updated: 2010/3/30 08:29, local time: 2024/8/31 17:24,
3.129.26.254:LOG IN
|
©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions? <A HREF="http://sxlist.com/Techref/microchip/math/mul/16x16rp.htm"> PIC Microcontoller Math Method Multiply 16x16 bit from Ravi Pailoor</A> |
Did you find what you needed? |
Welcome to sxlist.com!sales, advertizing, & kind contributors just like you! Please don't rip/copy (here's why Copies of the site on CD are available at minimal cost. |
Welcome to sxlist.com! |
.