Subversion Repositories rtf65002

; ============================================================================
;        __
;   \\__/ o\    (C) 2014  Robert Finch, Stratford
;    \  __ /    All rights reserved.
;     \/_//     robfinch<remove>@finitron.ca
;       ||
;  
;
; This source file is free software: you can redistribute it and/or modify 
; it under the terms of the GNU Lesser General Public License as published 
; by the Free Software Foundation, either version 3 of the License, or     
; (at your option) any later version.                                      
;                                                                          
; This source file is distributed in the hope that it will be useful,      
; but WITHOUT ANY WARRANTY; without even the implied warranty of           
; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            
; GNU General Public License for more details.                             
;                                                                          
; You should have received a copy of the GNU General Public License        
; along with this program.  If not, see <http://www.gnu.org/licenses/>.    
;
; This code calculates PI to 360 digits. It runs on a 65C816 processor. 
; The code was found at www.6502.org                                                           
; ============================================================================
;
P       EQU             2
Q       EQU             1193*2 + 2
R       EQU             Q + 2
SSS     EQU             R + 2

                jsr             INITSUB
                ldx             #359
                ldy             #1193
L1S:    
                phy
                pha
                phx
                stz             Q
;               txa
;               ldx             #5
;               wdm
;               xce
;               cpu             RTF65002
;               jsr             PRTNUM
;               clc
;               xce
;               cpu             W65C816S
;               rep             #$30
;               plx
;               phx
                tya
                tax
L2S:    
                txa

;               phx
;               ldx             #5
;               wdm
;               xce
;               cpu             RTF65002
;               jsr             PRTNUM
;               clc
;               xce
;               cpu             W65C816S
;               rep             #$30
;               plx
;               txa

                jsr             MULSUB
                sta             SSS
                lda             #10
                sta             Q
                jsr             ADJ1SUB
                lda             P-1,x
                jsr             UNADJ1SUB
                jsr             MULSUB
                clc
                adc             SSS
                sta             Q
                txa
                asl
                dea
                jsr             DIVSUB
                jsr             ADJ1SUB
                sta             P-1,x
                jsr             UNADJ1SUB
                dex
                bne             L2S
                lda             #10
                jsr             DIVSUB
                sta             P
                plx
                pla
                ldy             Q
                cpy             #10
                bcc             L3S
                ldy             #0
                ina
L3S:    
                cpx             #358
                bcc             L4S
                bne             L5S
                jsr             OUTPUTSUB
                lda             #46
L4S:    
                jsr             OUTPUTSUB
L5S:    
                tya
                eor             #48
                ply
                cpx             #358
                bcs             L6S
                dey
                dey
                dey
L6S:    
                dex
                beq             L7S
                jmp             L1S
L7S:
                jsr             OUTPUTSUB
                wdm
                xce
                cpu             RTF65002
                rts

                cpu             W65C816S
INITSUB:
                lda             #2
                ldx             #1192
IS1:
                jsr             ADJSUB
                sta             P,x
                jsr             UNADJSUB
                dex
                bpl             IS1
                rts

MULSUB:
                sta             R
                ldy             #16
M1S:    asl
                asl             Q
                bcc             M2S
                clc
                adc             R
M2S:    dey
                bne             M1S
                rts

DIVSUB:
                sta             R
                ldy             #16
                lda             #0
                asl             Q
D1S:    rol
                cmp             R
                bcc             D2S
                sbc             R
D2S:    rol             Q
                dey
                bne             D1S
                rts
                
ADJSUB:
                pha
                txa
                asl
                tax
                pla
                rts
UNADJSUB:       
                pha
                txa
                lsr
                tax
                pla
                rts
ADJ1SUB:
                pha
                txa
                asl
                tax
                pla
                dex
                rts
UNADJ1SUB:
                pha
                txa
                lsr
                tax
                pla
                inx
                rts

OUTPUTSUB:
        ; switching back to '816 mode will force the registers to 8 bit, so we
        ; have to save off their values, then restore them after the switch
                wdm             ; switch to 32 bit mode
                xce
                cpu             RTF65002
                jsr             DisplayChar
                clc             ; switch back to 816 mode
                xce
                cpu             W65C816S
                rts