PIC24FJ64GA306-I/MR Microchip Technology, PIC24FJ64GA306-I/MR Datasheet - Page 40

• Manufacturer Part Number: PIC24FJ64GA306-I/MR
• Description: 16-bit, 16 MIPS, 64 KB Flash, 8 KB RAM, 53 I/O, LCD, XLP W/Vbat 64 QFN 9x9x0.9mm
• Manufacturer: Microchip Technology

PIC24FJ128GA310 FAMILY
3.3
The PIC24F ALU is 16 bits wide and is capable of addi-
tion, subtraction, bit shifts and logic operations. Unless
otherwise mentioned, arithmetic operations are 2’s
complement in nature. Depending on the operation, the
ALU may affect the values of the Carry (C), Zero (Z),
Negative (N), Overflow (OV) and Digit Carry (DC)
Status bits in the SR register. The C and DC Status bits
operate as Borrow and Digit Borrow bits, respectively,
for subtraction operations.
The ALU can perform 8-bit or 16-bit operations,
depending on the mode of the instruction that is used.
Data for the ALU operation can come from the W
register array, or data memory, depending on the
addressing mode of the instruction. Likewise, output
data from the ALU can be written to the W register array
or a data memory location.
The PIC24F CPU incorporates hardware support for
both multiplication and division. This includes a
dedicated hardware multiplier and support hardware
for 16-bit divisor division.
3.3.1
The ALU contains a high-speed, 17-bit x 17-bit
multiplier. It supports unsigned, signed or mixed sign
operation in several multiplication modes:
1.
2.
3.
4.
5.
6.
7.
TABLE 3-2:
DS39996F-page 40
16-bit x 16-bit signed
16-bit x 16-bit unsigned
16-bit signed x 5-bit (literal) unsigned
16-bit unsigned x 16-bit unsigned
16-bit unsigned x 5-bit (literal) unsigned
16-bit unsigned x 16-bit signed
8-bit unsigned x 8-bit unsigned
Instruction
Arithmetic Logic Unit (ALU)
ASR
LSR
SL
MULTIPLIER
INSTRUCTIONS THAT USE THE SINGLE BIT AND MULTI-BIT SHIFT OPERATION
Arithmetic shift right source register by one or more bits.
Shift left source register by one or more bits.
Logical shift right source register by one or more bits.
3.3.2
The divide block supports signed and unsigned integer
divide operations with the following data sizes:
1.
2.
3.
4.
The quotient for all divide instructions ends up in W0
and the remainder in W1. Sixteen-bit signed and
unsigned DIV instructions can specify any W register
for both the 16-bit divisor (Wn), and any W register
(aligned) pair (W(m + 1):Wm) for the 32-bit dividend.
The divide algorithm takes one cycle per bit of divisor,
so both 32-bit/16-bit and 16-bit/16-bit instructions take
the same number of cycles to execute.
3.3.3
The PIC24F ALU supports both single bit and
single-cycle, multi-bit arithmetic and logic shifts.
Multi-bit shifts are implemented using a shifter block,
capable of performing up to a 15-bit arithmetic right
shift, or up to a 15-bit left shift, in a single cycle. All
multi-bit shift instructions only support Register Direct
Addressing for both the operand source and result
destination.
A full summary of instructions that use the shift
operation is provided in
Description
32-bit signed/16-bit signed divide
32-bit unsigned/16-bit unsigned divide
16-bit signed/16-bit signed divide
16-bit unsigned/16-bit unsigned divide
DIVIDER
MULTI-BIT SHIFT SUPPORT
 2010-2011 Microchip Technology Inc.
Table
3-2.