PIC18C242/JW Microchip Technology, PIC18C242/JW Datasheet - Page 64

• Manufacturer Part Number: PIC18C242/JW
• Description: IC MCU EPROM 8KX16 A/D 28CDIP
• Manufacturer: Microchip Technology
• Series: PIC® 18Cr

Specifications of PIC18C242/JW

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 40MHz
• Connectivity: I²C, SPI, UART/USART
• Peripherals: Brown-out Detect/Reset, LVD, POR, PWM, WDT
• Number Of I /o: 22
• Program Memory Size: 16KB (8K x 16)
• Program Memory Type: EPROM, UV
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 4.2 V ~ 5.5 V
• Data Converters: A/D 5x10b
• Oscillator Type: External
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 28-CDIP (0.300", 7.62mm) Window
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -

PIC18CXX2
EXAMPLE 6-3:
Example 6-4 shows the sequence to do a 16 x 16
signed multiply. Equation 6-2 shows the algorithm
used. The 32-bit result is stored in four registers,
RES3:RES0. To account for the sign bits of the argu-
ments, each argument pairs’ Most Significant bit (MSb)
is tested and the appropriate subtractions are done.
EQUATION 6-2:
RES3:RES0
DS39026C-page 62
;
;
;
=
=
MOVF
MULWF
MOVFF
MOVFF
MOVF
MULWF
MOVFF
MOVFF
MOVF
MULWF
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
MOVF
MULWF
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
ARG1H:ARG1L
(ARG1H
(ARG1H
(ARG1L
(ARG1L
(-1
(-1
ARG1L, W
ARG2L
PRODH, RES1 ;
PRODL, RES0 ;
ARG1H, W
ARG2H
PRODH, RES3 ;
PRODL, RES2 ;
ARG1L, W
ARG2H
PRODL, W
RES1,
PRODH, W
RES2,
WREG,
RES3,
ARG1H, W
ARG2L
PRODL, W
RES1,
PRODH, W
RES2,
WREG,
RES3,
ARG2H<7>
ARG1H<7>
ARG2H
ARG2L
ARG2H
ARG2L)+
16 x 16 UNSIGNED
MULTIPLY ROUTINE
16 x 16 SIGNED
MULTIPLICATION
ALGORITHM
F
F
F
F
F
F
F
F
ARG2H:ARG2L
2
2
2
ARG1H:ARG1L
ARG2H:ARG2L
; ARG1L * ARG2L ->
; PRODH:PRODL
; ARG1H * ARG2H ->
; PRODH:PRODL
; ARG1L * ARG2H ->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
;
; ARG1H * ARG2L ->
; PRODH:PRODL
;
; Add cross
; products
;
;
;
16
8
8
)+
)+
)+
2
2
16
16
)+
)
EXAMPLE 6-4:
;
;
;
;
;
SIGN_ARG1
;
CONT_CODE
MULWF
MULWF
MULWF
MULWF
BTFSS
BTFSS
MOVF
MOVFF
MOVFF
MOVF
MOVFF
MOVFF
MOVF
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
MOVF
MOVF
ADDWF
MOVF
ADDWFC
CLRF
ADDWFC
BRA
MOVF
SUBWF
MOVF
SUBWFB
BRA
MOVF
SUBWF
MOVF
SUBWFB
:
ARG2H, 7
ARG1H, 7
ARG1L, W
ARG2L
PRODH, RES1 ;
PRODL, RES0 ;
ARG1H, W
ARG2H
PRODH, RES3 ;
PRODL, RES2 ;
ARG1L, W
ARG2H
PRODL, W
RES1,
PRODH, W
RES2,
WREG,
RES3,
ARG1H, W
ARG2L
PRODL, W
RES1,
PRODH, W
RES2, F
WREG, F
RES3, F
SIGN_ARG1
ARG1L, W
RES2
ARG1H, W
RES3
CONT_CODE
ARG2L, W
RES2
ARG2H, W
RES3
16 x 16 SIGNED
MULTIPLY ROUTINE
F
F
F
F
F
2001 Microchip Technology Inc.
; ARG1L * ARG2L ->
; ARG1H * ARG2H ->
; ARG1L * ARG2H ->
; ARG1H * ARG2L ->
; ARG2H:ARG2L neg?
; ARG1H:ARG1L neg?
; PRODH:PRODL
; PRODH:PRODL
; PRODH:PRODL
;
; Add cross
; products
;
;
;
;
; PRODH:PRODL
;
; Add cross
; products
;
;
;
; no, check ARG1
;
;
;
; no, done
;
;
;