PIC17C756A MICROCHIP [Microchip Technology], PIC17C756A Datasheet - Page 68

• Manufacturer Part Number: PIC17C756A
• Description: High-Performance 8-bit CMOS EPROM Microcontrollers with 10-bit A/D
• Manufacturer: MICROCHIP [Microchip Technology]

PIC17C7XX
Example 9-3 shows the sequence to do a 16 x 16
unsigned multiply. Equation 9-1 shows the algorithm
that is used. The 32-bit result is stored in 4 registers,
RES3:RES0.
EQUATION 9-1:
DS30289B-page 68
RES3:RES0 =
=
ARG1H:ARG1L ARG2H:ARG2L
(ARG1H ARG2H 2
(ARG1H ARG2L 2
(ARG1L ARG2H 2
(ARG1L ARG2L)
16 x 16 UNSIGNED
MULTIPLICATION
ALGORITHM
8
8
16
)
)
)
+
+
+
EXAMPLE 9-3:
;
;
;
MOVFP
MULWF
MOVPF
MOVPF
MOVFP
MULWF
MOVPF
MOVPF
MOVFP
MULWF
MOVFP
ADDWF
MOVFP
ADDWFC
CLRF
ADDWFC
MOVFP
MULWF
MOVFP
ADDWF
MOVFP
ADDWFC
CLRF
ADDWFC
ARG1L, WREG
ARG2L
PRODH, RES1 ;
PRODL, RES0 ;
ARG1H, WREG
ARG2H
PRODH, RES3 ;
PRODL, RES2 ;
ARG1L, WREG
ARG2H
PRODL, WREG ;
RES1, F
PRODH, WREG ;
RES2, F
WREG, F
RES3, F
ARG1H, WREG ;
ARG2L
PRODL, WREG ;
RES1, F
PRODH, WREG ;
RES2, F
WREG, F
RES3, F
16 x 16 UNSIGNED
MULTIPLY ROUTINE
2000 Microchip Technology Inc.
; ARG1L * ARG2L ->
;
; ARG1H * ARG2H ->
;
; ARG1L * ARG2H ->
;
; Add cross
;
;
;
; ARG1H * ARG2L ->
;
; Add cross
;
;
;
PRODH:PRODL
PRODH:PRODL
PRODH:PRODL
PRODH:PRODL
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