AVR Instruction Set Nomenclature: Status Register (SREG ...

SBCI - Subtract Immediate with Carry
Description:
Subtracts a constant from a register and subtracts with the C flag and places the result in the destination register Rd.
Operation:
(i) Rd ← Rd - K - C
Syntax: Operands: Program Counter:
(i) SBCI Rd,K 16 ≤ d ≤ 31, 0 ≤ K ≤ 255 PC ← PC + 1
102
16-bit Opcode:
Status Register and Boolean Formula:
H: Rd3• K3 + K3• R3 + R3 •Rd3
Set if there was a borrow from bit 3; cleared otherwise
S: N ⊕ V, For signed tests.
V: Rd7 •K7• R7 +Rd7 •K7 •R7
Set if two’s complement overflow resulted from the operation; cleared otherwise.
N: R7
Set if MSB of the result is set; cleared otherwise.
Z: R7• R6 •R5• R4• R3 •R2• R1• R0• Z
Previous value remains unchanged when the result is zero; cleared otherwise.
C: Rd7 •K7+ K7 • R7 +R7 •Rd7
Set if the absolute value of the constant plus previous carry is larger than the absolute value of Rd; cleared otherwise.
R (Result) equals Rd after the operation.
Example:
0100 KKKK dddd KKKK
I T H S V N Z C
- - ⇔ ⇔ ⇔ ⇔ ⇔ ⇔
Words: 1 (2 bytes)
Cycles: 1
subi r16,$23
; Subtract $4F23 from r17:r16
; Subtract low byte
sbci r17,$4F ; Subtract with carry high byte
Instruction Set