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© 2005-2011 Microchip Technology Inc. DS70157F-page 331
Section 5. Instruction Descriptions
Instruction
Descriptions
5
MULW.UU
Integer 16x16-bit Unsigned Multiply with 16-bit Result
Implemented in: PIC24F PIC24H PIC24E dsPIC30F dsPIC33F dsPIC33E
X X
Syntax: {label:} MULW.UU Wb, Ws, Wnd
[Ws],
[Ws++],
[Ws--],
[++Ws],
[--Ws],
Operands: Wb [W0 ... W15]
Ws [W0 ... W15]
Wnd [W0, W2, W4 ... W12]
Operation: unsigned (Wb) * unsigned (Ws) Wnd
Status Affected: None
Encoding:
1011 1000 0www wddd dppp ssss
Description: Multiply the contents of Wb with the contents of Ws, and store the result
in a working registers, which must be an even numbered working
register). Both source operands and the result are interpreted as
unsigned integers. Register direct addressing must be used for Wb and
Wnd. Register direct or indirect addressing may be used for Ws.
The ‘w’ bits select the address of the base register.
The ‘d’ bits select the address of the lower destination register.
The ‘p’ bits select the source Address mode.
The ‘s’ bits select the source register.
Note 1: This instruction operates in Word mode only.
2: Wnd must be an even working register.
3: Wnd may not be W14, since W15<0> is fixed to zero.
4: The IF bit and the US<1:0> bits in the CORCON register have
no effect on this operation.
Words: 1
Cycles:
1
(1)
Note 1:
In dsPIC33E and PIC24E devices, the listed cycle count does not apply to read and
read-modify-write operations on non-CPU Special Function Registers. For more
details, see
Note 3
in
Section 3.2.1 “Multi-Cycle Instructions”
.
Example 1:
MULW.UU W4, W0, W2 ; Multiply W4*W0 (unsigned-unsigned)
; Store the result to W2
Before
Instruction
After
Instruction
W0 FFFF W0 FFFF
W2 2300 W2 0001
W4 FFFF W4 FFFF
SR 0000 SR 0000

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