Sub/subb src, Sub/subb src -30, Maxq7667 user’s guide – Maxim Integrated MAXQ7667 User Manual

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MAXQ7667 User’s Guide

SUB/SUBB src

Subtract/Subtract with Borrow

Description:

Subtracts the specified src from the active accumulator (Acc) and returns the result back to the active accumula-

tor. The SUBB additionally subtracts the borrow (Carry Flag), which may have resulted from previous subtraction.

For the complete list of src specifiers, reference the MOVE instruction. The MAXQ7667 may use the PFX[n] register

to supply the high byte of data for 8-bit sources.

Status Flags:

C, S, Z, OV

SUB Operation:

Acc

← Acc - src

Encoding:

Example(s):

; Acc = 2345h to start, A[1]= 1250h

SUB

A[1]

; Acc = 10F5h, C=0, S=0, Z=0, OV=0

SUB

A[1]

; Acc = FEA5h, C=1, S=1, Z=0, OV=0

SUB

A[2]

; A[2] =7FFFh

;

→ Acc = 7EA6h; C=0, S=0, Z=0, OV=1

SUBB Operation: Acc

← Acc - (src + C)

Encoding:

Example(s):

; Acc = 2345h, A[1]= 1250h, C=1

SUBB

A[1]

; Acc = 10F4h, C=0, S=0, Z=0

SUBB

A[1]

; Acc = FEA4h, C=1, S=1, Z=0

Special Notes:

The active accumulator (Acc) is not allowed as the src for these operations.

f101 1010

ssss ssss

f111 1010

ssss ssss