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DS4830A User’s Guide

228

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 accumulator. 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.

Because the source is limited to 8 bits, the PFX[n] register is used to

supply the high-byte of data for 16 bit sources.

Status Flags: C, S, Z, OV

SUB Operation: Acc  Acc - src

Encoding: 15 0

f101

1010

ssss

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: 15 0

f111

1010

ssss

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.

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Maxim-integrated DS4830A Optical Microcontroller Manuale Utente Pagina 228