PIC18F25K80 MICROCHIP [Microchip Technology], PIC18F25K80 Datasheet - Page 152

• Manufacturer Part Number: PIC18F25K80
• Manufacturer: MICROCHIP [Microchip Technology]

PIC18F66K80 FAMILY
Example 9-3
unsigned multiplication.
algorithm that is used. The 32-bit result is stored in four
registers (RES3:RES0).
EQUATION 9-1:
EXAMPLE 9-3:
Example 9-4
signed multiply.
used. The 32-bit result is stored in four registers
(RES3:RES0). To account for the sign bits of the
arguments, the MSb for each argument pair is tested
and the appropriate subtractions are done.
DS39977C-page 152
RES3:RES0
;
;
;
MOVF
MULWF
MOVFF
MOVFF
MOVF
MULWF
MOVFF
MOVFF
MOVF
MULWF
MOVF
ADDWF
MOVF
ADDWFC RES2, F
CLRF
ADDWFC RES3, F
MOVF
MULWF
MOVF
ADDWF
MOVF
ADDWFC RES2, F
CLRF
ADDWFC RES3, F
shows the sequence to do a 16 x 16
shows the sequence to do a 16 x 16
=
=
ARG1L, W
ARG2L
PRODH, RES1
PRODL, RES0
ARG1H, W
ARG2H
PRODH, RES3
PRODL, RES2
ARG1L, W
ARG2H
PRODL, W
RES1, F
PRODH, W
WREG
ARG1H, W
ARG2L
PRODL, W
RES1, F
PRODH, W
WREG
Equation 9-2
ARG1H:ARG1L  ARG2H:ARG2L
(ARG1H  ARG2H  2
(ARG1H  ARG2L  2
(ARG1L  ARG2H  2
(ARG1L  ARG2L)
16 x 16 UNSIGNED
MULTIPLICATION
ALGORITHM
16 x 16 UNSIGNED
MULTIPLY ROUTINE
Equation 9-1
shows the algorithm
; ARG1L * ARG2L->
; PRODH:PRODL
;
;
; ARG1H * ARG2H->
; PRODH:PRODL
;
;
; ARG1L * ARG2H->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
;
; ARG1H * ARG2L->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
8
8
16
) +
) +
) +
shows the
Preliminary
EQUATION 9-2:
EXAMPLE 9-4:
RES3:RES0=
;
;
;
;
SIGN_ARG1
;
CONT_CODE
MOVF
MULWF
MOVFF
MOVFF
MOVF
MULWF
MOVFF
MOVFF
MOVF
MULWF
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
MOVF
MULWF
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
BTFSS
BRA
MOVF
SUBWF
MOVF
SUBWFB
BTFSS
BRA
MOVF
SUBWF
MOVF
SUBWFB
:
=
SIGN_ARG1
ARG1L, W
ARG2L
PRODH, RES1 ;
PRODL, RES0 ;
ARG1H, W
ARG2H
PRODH, RES3 ;
PRODL, RES2 ;
ARG1L, W
ARG2H
PRODL, W
RES1, F
PRODH, W
RES2, F
WREG
RES3, F
ARG1H, W
ARG2L
PRODL, W
RES1, F
PRODH, W
RES2, F
WREG
RES3, F
ARG2H, 7
ARG1L, W
RES2
ARG1H, W
RES3
ARG1H, 7
CONT_CODE
ARG2L, W
RES2
ARG2H, W
RES3
ARG1H:ARG1L  ARG2H:ARG2L
(ARG1H  ARG2H  2
(ARG1H  ARG2L  2
(ARG1L  ARG2H  2
(ARG1L  ARG2L) +
(-1  ARG2H<7>  ARG1H:ARG1L  2
(-1  ARG1H<7>  ARG2H:ARG2L  2
16 x 16 SIGNED
MULTIPLICATION
ALGORITHM
16 x 16 SIGNED MULTIPLY
ROUTINE
 2011 Microchip Technology Inc.
; ARG1L * ARG2L ->
; PRODH:PRODL
; ARG1H * ARG2H ->
; PRODH:PRODL
; ARG1L * ARG2H ->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
;
; ARG1H * ARG2L ->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
; ARG2H:ARG2L neg?
; no, check ARG1
;
;
;
;
; ARG1H:ARG1L neg?
; no, done
;
;
;
8
8
16
) +
) +
) +
16
16
) +
)