PIC16C55X
DS40143D-page 64
Preliminary
2002 Microchip Technology Inc.
SUBWF
Subtract W from f
Syntax:
[
label ] SUBWF f,d
Operands:
0
≤ f ≤ 127
d
∈ [0,1]
Operation:
(f) - (W)
→ (dest)
Status
Affected:
C, DC, Z
Encoding:
00
0010
dfff
ffff
Description:
Subtract (2’s complement method)
W register from register 'f'. If 'd' is 0 the
result is stored in the W register. If 'd' is 1
the result is stored back in register 'f'.
Words:
1
Cycles:
1
Example 1:
SUBWF
REG1,1
Before Instruction
REG1 =
3
W=
2
C=
?
After Instruction
REG1 =
1
W=
2
C
=
1; result is positive
Example 2:
Before Instruction
REG1 =
2
W=
2
C=
?
After Instruction
REG1 =
0
W=
2
C
=
1; result is zero
Example 3:
Before Instruction
REG1 =
1
W=
2
C=
?
After Instruction
REG1 =
0xFF
W=
2
C
=
0; result is negative
SWAPF
Swap Nibbles in f
Syntax:
[
label ] SWAPF f,d
Operands:
0
≤ f ≤ 127
d
∈ [0,1]
Operation:
(f<3:0>)
→ (dest<7:4>),
(f<7:4>)
→ (dest<3:0>)
Status Affected:
None
Encoding:
00
1110
dfff
ffff
Description:
The upper and lower nibbles of
register 'f' are exchanged. If 'd' is 0
the result is placed in W register. If 'd'
is 1 the result is placed in register 'f'.
Words:
1
Cycles:
1
Example
SWAPF
REG,
0
Before Instruction
REG1
= 0xA5
After Instruction
REG1
= 0xA5
W
= 0x5A
TRIS
Load TRIS Register
Syntax:
[
label ] TRIS
f
Operands:
5
≤ f ≤ 7
Operation:
(W)
→ TRIS register f;
Status Affected:
None
Encoding:
00
0000
0110
0fff
Description:
The instruction is supported for code
compatibility with the PIC16C5X
products. Since TRIS registers are
readable and writable, the user can
directly address them.
Words:
1
Cycles:
1
Example
To maintain upward compatibility
with future PICmicro products, do
not use this instruction.