+/
+/
+/ routine to add the two centennial numbers
+/ pointed to by r2 and r3.
+/ a pointer to the result is returned in r1
+/ r2 and r3 are preserved
+/
+/ mov ptr1,r2
+/ mov ptr2,r3
+/ jsr pc,add3
+/ mov r1,...
+/
+add3: mov r0,-(sp)
+ mov r4,-(sp)
+ mov r5,-(sp)
+ mov r3,-(sp)
+ mov r2,-(sp)
+/
+/ allocate a new string whose length is
+/ the max of the two addends.
+/
+ mov w(r2),r0
+ sub a(r2),r0
+ mov w(r3),r4
+ sub a(r3),r4
+ cmp r0,r4
+ bgt 1f
+ mov r4,r0
+1: mov r0,r4
+ jsr pc,allocate
+ mov r1,-(sp)
+/
+/ get everything ready
+/
+ mov 2(sp),r1
+ jsr pc,rewind
+ mov 4(sp),r1
+ jsr pc,rewind
+ clr carry
+/
+/ now add them
+/
+2: dec r4
+ blt 3f
+ mov 2(sp),r1 /r2
+ jsr pc,getchar
+ mov r0,r5
+ mov 4(sp),r1 /r3
+ jsr pc,getchar
+ add r5,r0
+ add carry,r0
+ clr carry
+ cmp r0,$100.
+ blt 1f
+ sub $100.,r0
+ mov $1,carry
+1:
+ tstb r0
+ bpl 1f
+ add $100.,r0
+ mov $-1,carry
+1: mov (sp),r1 /r1
+ jsr pc,putchar
+ br 2b
+/
+/ perhaps there is an extra digit
+/
+3: mov carry,r0
+ beq 2f
+ mov (sp),r1 /r1
+ jsr pc,putchar
+/
+/ strip leading zeros
+/
+2:
+ jsr pc,fsfile
+2: jsr pc,backspace
+ bes 2f
+ beq 2b
+ inc r(r1)
+2: mov r(r1),w(r1)
+/
+/ strip leading 99's
+/
+ jsr pc,fsfile
+ jsr pc,backspace
+ cmpb r0,$-1
+ bne 1f
+2:
+ jsr pc,backspace
+ bes 2f
+ cmpb r0,$99.
+ beq 2b
+ jsr pc,getchar
+2:
+ mov $-1,r0
+ jsr pc,alterchar
+ mov r(r1),w(r1)
+/
+/ restore and return
+/
+1:
+ mov (sp)+,r1
+ mov (sp)+,r2
+ mov (sp)+,r3
+ mov (sp)+,r5
+ mov (sp)+,r4
+ mov (sp)+,r0
+ rts pc
+/
+.bss
+carry: .=.+2
+.text
+/
+/
+/ routine to change the sign of the centennial number
+/ pointed to by r1.
+/ negative numbers are stored in 100's complement form with
+/ -1 as the high order digit; the second digit is not 99.
+/
+/ mov ...,r1
+/ jsr pc,chsign
+/
+chsign:
+ mov r1,-(sp)
+ mov r0,-(sp)
+ jsr pc,rewind
+ clr chcarry
+/
+1:
+ jsr pc,lookchar
+ bes 1f
+ negb r0
+ sub chcarry,r0
+ mov $1,chcarry
+ add $100.,r0
+ cmpb $100.,r0
+ bgt 2f
+ sub $100.,r0
+ clr chcarry
+2:
+ jsr pc,alterchar
+ br 1b
+/
+1:
+ clr r0
+ sub chcarry,r0
+ beq 2f
+ jsr pc,putchar
+ jsr pc,fsfile
+ jsr pc,backspace
+ jsr pc,backspace
+ cmp r0,$99.
+ bne 1f
+ mov r(r1),w(r1)
+ mov $-1,r0
+ jsr pc,putchar
+ br 1f
+/
+2:
+ jsr pc,fsfile
+ jsr pc,backspace
+ bne 1f
+ mov r(r1),w(r1)
+/
+1:
+ mov (sp)+,r0
+ mov (sp)+,r1
+ rts pc
+/
+.bss
+chcarry: .=.+2
+.text
+/
+/
+/
+/
+/ routine to multiply the two centennial numbers
+/ pointed to by r2 and r3.
+/ a pointer to the result is returned in r1
+/ r2 and r3 are preserved
+/
+/ mov ptr1,r2
+/ mov ptr2,r3
+/ jsr pc,mul3
+/ mov r1,...
+/
+/ save registers and make space for temps
+/
+mul3:
+ mov r5,-(sp)
+ mov r3,-(sp) /arg2
+ mov r2,-(sp) /arg1
+ mov r0,-(sp)
+ tst -(sp) /result
+ tst -(sp) /arg1
+ tst -(sp) /arg2
+ tst -(sp) /carry
+/
+/ compute sign of result and make args positive
+/
+ clr outsign
+ mov r2,r1
+ jsr pc,fsfile
+ jsr pc,backspace
+ bmi 2f
+ mov r2,4(sp) /arg1
+ br 1f
+2:
+ jsr pc,length
+ jsr pc,allocate
+ mov r1,4(sp)
+ mov r2,r0
+ jsr pc,move
+ jsr pc,chsign
+ com outsign
+1:
+ mov r3,r1
+ jsr pc,fsfile
+ jsr pc,backspace
+ bmi 2f
+ mov r3,2(sp) /arg2
+ br 1f
+2:
+ mov r3,r1
+ jsr pc,length
+ jsr pc,allocate
+ mov r1,2(sp)
+ mov r3,r0
+ jsr pc,move
+ jsr pc,chsign
+ com outsign
+1:
+/
+/ compute the length of the result and
+/ allocate space for it
+/
+ mov w(r2),r0
+ sub a(r2),r0
+ add w(r3),r0
+ sub a(r3),r0
+ jsr pc,allocate
+ jsr pc,zero
+ mov r1,6(sp) /result
+ clr offset
+ mov 2(sp),r1 /arg2
+ jsr pc,rewind
+/
+/ work on next digit of arg2, starting over on arg1
+/
+1: mov 4(sp),r1 /arg1
+ jsr pc,rewind
+ mov 2(sp),r1 /arg2
+ jsr pc,getchar
+ bes 3f
+ mov r0,r2
+ mov 6(sp),r1 /result
+ jsr pc,rewind
+ add offset,r(r1)
+ clr 0(sp) /carry
+/
+/ work on next digit of arg3
+/ form the product of the two digits,
+/ add to what is already there and add in old carry
+/ to generate new dit and new carry.
+/
+2: mov 4(sp),r1 /arg1
+ jsr pc,getchar
+ bes 2f
+ mov r0,r3
+ mpy r2,r3
+ add (sp),r3 /carry
+ mov 6(sp),r1 /result
+ jsr pc,lookchar
+ add r0,r3
+ mov r3,r1
+ clr r0
+ dvd $100.,r0
+ mov r0,(sp) /carry
+ mov r1,r0
+ mov 6(sp),r1 /result
+ jsr pc,alterchar
+ br 2b
+/
+2:
+ inc offset
+ tst (sp) /carry
+ beq 1b
+ mov 6(sp),r1 /result
+ jsr pc,lookchar
+ add (sp),r0 /carry
+ jsr pc,alterchar
+ br 1b
+/
+3:
+/
+/ change sign of result if necessary
+/
+ tst outsign
+ bpl 1f
+ mov 6(sp),r1 /result
+ jsr pc,chsign
+/
+/ release dregs if necessary
+/
+1:
+ cmp 2(sp),14(sp)
+ beq 1f
+ mov 2(sp),r1
+ jsr pc,release
+1:
+ cmp 4(sp),12(sp)
+ beq 1f
+ mov 4(sp),r1
+ jsr pc,release
+1:
+/
+/ restore registers and return
+/
+ tst (sp)+
+ tst (sp)+
+ tst (sp)+
+ mov (sp)+,r1
+ mov (sp)+,r0
+ mov (sp)+,r2
+ mov (sp)+,r3
+ mov (sp)+,r5
+ rts pc
+/
+.bss
+outsign: .=.+2
+offset: .=.+2
+k: .=.+2
+kptr: .=.+2
+.text
+/
projects / unix-history / commitdiff