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PGP 1.0
TITLE fprims ; Fast 8086 assembly primitives for add, subtract, rotate left, ; and set precision bits for multiprecision integers. ; Callable from Microsoft C or Turbo C. ; Implemented Jan 1987 by Zhahai Stewart. ; Used by Philip Zimmermann's RSA public key cryptography library. ; Much faster primitives that implement a combined multiply/modulo ; operation are available by contacting Philip Zimmermann, ; at Boulder Software Engineering, phone (303)444-4541 ; Static Name Aliases ; _TEXT SEGMENT BYTE PUBLIC 'CODE' _TEXT ENDS CONST SEGMENT WORD PUBLIC 'CONST' CONST ENDS _BSS SEGMENT WORD PUBLIC 'BSS' _BSS ENDS _DATA SEGMENT WORD PUBLIC 'DATA' _DATA ENDS DGROUP GROUP CONST, _BSS, _DATA ASSUME CS: _TEXT, DS: DGROUP, SS: DGROUP, ES: DGROUP PUBLIC _P_SETP ;set global precision, maximum of 1024 bits PUBLIC _P_ADDC ;multiprecision add with carry PUBLIC _P_SUBB ;multiprecision subtract with borrow PUBLIC _P_ROTL ;multiprecision rotate left 1 bit _DATA SEGMENT _DATA ENDS _TEXT SEGMENT mswoff dw (?) adcx dw (?) sbbx dw (?) rclx dw (?) ;-------------------------------------------------------------- ; precision=bp+4 precision in bits ; prec means precision in wds PUBLIC _P_SETP _P_SETP PROC NEAR push bp mov bp,sp mov ax,[bp+4] ; add ax,15 round up ; shr ax,4 number of words ; dec ax number - 1 ; shl ax,4 back to number of bits: 16 * (prec - 1) dec ax ; faster alternate way to do same thing and al,0F0h cmp ax,1008 ; 16 * (64-1) jg x_setp ; out of range shr ax,1 ; ax = 8 * (prec - 1) shr ax,1 ; ax = 4 * (prec - 1) mov bx,offset adc01 sub bx,ax mov cs:[adcx],bx ; adcx = &adc01 - 4 * (prec - 1) mov bx,offset sbb01 sub bx,ax mov cs:[sbbx],bx ; sbbx = &sbb01 - 4 * (prec - 1) mov bx,offset rcl01 shr ax,1 ; ax = 2 * (prec - 1) mov cs:[mswoff],ax ; mswoff = 2 * (prec-1) = msword offset sub bx,ax shr ax,1 ; ax = prec - 1 sub bx,ax mov cs:[rclx],bx ; rclx = &rcl01 - 3 * (prec - 1) x_setp: pop bp ret _P_SETP ENDP ;-------------------------------------------------------------- ; r1=bp+4 ; r2=bp+6 ; carry=bp+8 PUBLIC _P_ADDC _P_ADDC PROC NEAR push bp mov bp,sp push si push di mov di,[bp+4] ; r1 mov si,[bp+6] ; r2 add di,cs:[mswoff] ; offset to msw cld ; go fwd mov al,0FFh ; set cy flag if carry non-zero add al,[bp+8] ; carry in call cs:[adcx] mov ax,0 ; don't affect flags rcl ax,1 ; set ax = 0 if no borrow, 1 if borrow out pop di pop si mov sp,bp pop bp ret _P_ADDC ENDP ;-------------------------------------------------------------- ; r1=bp+4 ; r2=bp+6 ; borrow=bp+8 PUBLIC _P_SUBB _P_SUBB PROC NEAR push bp mov bp,sp push si push di mov di,[bp+4] ; r1 mov si,[bp+6] ; r2 add di,cs:[mswoff] ; offset to msw cld ; go fwd mov al,0FFh ; set cy flag if borrow non-zero add al,[bp+8] ; borrow call cs:[sbbx] mov ax,0 ; don't affect flags rcl ax,1 ; set ax = 0 if no borrow, 1 if borrow out pop di pop si mov sp,bp pop bp ret _P_SUBB ENDP ;-------------------------------------------------------------- ; r1=bp+4 ; c=bp+6 PUBLIC _P_ROTL _P_ROTL PROC NEAR push bp mov bp,sp push di mov di,[bp+4] ; r1 add di,cs:[mswoff] ; offset to msw mov al,0FFh add al,[bp+6] ; c (carry) call cs:[rclx] mov ax,0 ; don't affect flags rcl ax,1 ; set ax = 0 if no carry, 1 if carry out pop di mov sp,bp pop bp ret _P_ROTL ENDP ;======================================================================== dummy proc near adc64: lodsw adc [di-126],ax lodsw adc [di-124],ax lodsw adc [di-122],ax lodsw adc [di-120],ax lodsw adc [di-118],ax lodsw adc [di-116],ax lodsw adc [di-114],ax lodsw adc [di-112],ax lodsw adc [di-110],ax lodsw adc [di-108],ax lodsw adc [di-106],ax lodsw adc [di-104],ax lodsw adc [di-102],ax lodsw adc [di-100],ax lodsw adc [di-98],ax lodsw adc [di-96],ax lodsw adc [di-94],ax lodsw adc [di-92],ax lodsw adc [di-90],ax lodsw adc [di-88],ax lodsw adc [di-86],ax lodsw adc [di-84],ax lodsw adc [di-82],ax lodsw adc [di-80],ax lodsw adc [di-78],ax lodsw adc [di-76],ax lodsw adc [di-74],ax lodsw adc [di-72],ax lodsw adc [di-70],ax lodsw adc [di-68],ax lodsw adc [di-66],ax lodsw adc [di-64],ax lodsw adc [di-62],ax lodsw adc [di-60],ax lodsw adc [di-58],ax lodsw adc [di-56],ax lodsw adc [di-54],ax lodsw adc [di-52],ax lodsw adc [di-50],ax lodsw adc [di-48],ax lodsw adc [di-46],ax lodsw adc [di-44],ax lodsw adc [di-42],ax lodsw adc [di-40],ax lodsw adc [di-38],ax lodsw adc [di-36],ax lodsw adc [di-34],ax lodsw adc [di-32],ax lodsw adc [di-30],ax lodsw adc [di-28],ax lodsw adc [di-26],ax lodsw adc [di-24],ax lodsw adc [di-22],ax lodsw adc [di-20],ax lodsw adc [di-18],ax lodsw adc [di-16],ax lodsw adc [di-14],ax lodsw adc [di-12],ax lodsw adc [di-10],ax lodsw adc [di-8],ax lodsw adc [di-6],ax lodsw adc [di-4],ax lodsw adc [di-2],ax adc01: lodsw adc [di],ax ret sbb64: lodsw sbb [di-126],ax lodsw sbb [di-124],ax lodsw sbb [di-122],ax lodsw sbb [di-120],ax lodsw sbb [di-118],ax lodsw sbb [di-116],ax lodsw sbb [di-114],ax lodsw sbb [di-112],ax lodsw sbb [di-110],ax lodsw sbb [di-108],ax lodsw sbb [di-106],ax lodsw sbb [di-104],ax lodsw sbb [di-102],ax lodsw sbb [di-100],ax lodsw sbb [di-98],ax lodsw sbb [di-96],ax lodsw sbb [di-94],ax lodsw sbb [di-92],ax lodsw sbb [di-90],ax lodsw sbb [di-88],ax lodsw sbb [di-86],ax lodsw sbb [di-84],ax lodsw sbb [di-82],ax lodsw sbb [di-80],ax lodsw sbb [di-78],ax lodsw sbb [di-76],ax lodsw sbb [di-74],ax lodsw sbb [di-72],ax lodsw sbb [di-70],ax lodsw sbb [di-68],ax lodsw sbb [di-66],ax lodsw sbb [di-64],ax lodsw sbb [di-62],ax lodsw sbb [di-60],ax lodsw sbb [di-58],ax lodsw sbb [di-56],ax lodsw sbb [di-54],ax lodsw sbb [di-52],ax lodsw sbb [di-50],ax lodsw sbb [di-48],ax lodsw sbb [di-46],ax lodsw sbb [di-44],ax lodsw sbb [di-42],ax lodsw sbb [di-40],ax lodsw sbb [di-38],ax lodsw sbb [di-36],ax lodsw sbb [di-34],ax lodsw sbb [di-32],ax lodsw sbb [di-30],ax lodsw sbb [di-28],ax lodsw sbb [di-26],ax lodsw sbb [di-24],ax lodsw sbb [di-22],ax lodsw sbb [di-20],ax lodsw sbb [di-18],ax lodsw sbb [di-16],ax lodsw sbb [di-14],ax lodsw sbb [di-12],ax lodsw sbb [di-10],ax lodsw sbb [di-8],ax lodsw sbb [di-6],ax lodsw sbb [di-4],ax lodsw sbb [di-2],ax sbb01: lodsw sbb [di],ax ret rcl64: rcl word ptr [di-126],1 rcl word ptr [di-124],1 rcl word ptr [di-122],1 rcl word ptr [di-120],1 rcl word ptr [di-118],1 rcl word ptr [di-116],1 rcl word ptr [di-114],1 rcl word ptr [di-112],1 rcl word ptr [di-110],1 rcl word ptr [di-108],1 rcl word ptr [di-106],1 rcl word ptr [di-104],1 rcl word ptr [di-102],1 rcl word ptr [di-100],1 rcl word ptr [di-98],1 rcl word ptr [di-96],1 rcl word ptr [di-94],1 rcl word ptr [di-92],1 rcl word ptr [di-90],1 rcl word ptr [di-88],1 rcl word ptr [di-86],1 rcl word ptr [di-84],1 rcl word ptr [di-82],1 rcl word ptr [di-80],1 rcl word ptr [di-78],1 rcl word ptr [di-76],1 rcl word ptr [di-74],1 rcl word ptr [di-72],1 rcl word ptr [di-70],1 rcl word ptr [di-68],1 rcl word ptr [di-66],1 rcl word ptr [di-64],1 rcl word ptr [di-62],1 rcl word ptr [di-60],1 rcl word ptr [di-58],1 rcl word ptr [di-56],1 rcl word ptr [di-54],1 rcl word ptr [di-52],1 rcl word ptr [di-50],1 rcl word ptr [di-48],1 rcl word ptr [di-46],1 rcl word ptr [di-44],1 rcl word ptr [di-42],1 rcl word ptr [di-40],1 rcl word ptr [di-38],1 rcl word ptr [di-36],1 rcl word ptr [di-34],1 rcl word ptr [di-32],1 rcl word ptr [di-30],1 rcl word ptr [di-28],1 rcl word ptr [di-26],1 rcl word ptr [di-24],1 rcl word ptr [di-22],1 rcl word ptr [di-20],1 rcl word ptr [di-18],1 rcl word ptr [di-16],1 rcl word ptr [di-14],1 rcl word ptr [di-12],1 rcl word ptr [di-10],1 rcl word ptr [di-8],1 rcl word ptr [di-6],1 rcl word ptr [di-4],1 rcl word ptr [di-2],1 rcl01: rcl word ptr [di],1 ret dummy endp _TEXT ENDS END
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