Instruction Set
3-67
RISC 16-Bit CPU
SUBC[.W]SBB[.W]
Subtract source and borrow/.NOT. carry from destination
SUBC.B,SBB.B
Subtract source and borrow/.NOT. carry from destination
Syntax
SUBC
src,dst or
SUBC.W
src,dst
or
SBB
src,dst or
SBB.W
src,dst
SUBC.B
src,dst
or
SBB.B
src,dst
Operation
dst + .NOT.src + C −> dst
or
(dst − src − 1 + C −> dst)
Description
The source operand is subtracted from the destination operand by adding the
source operand’s 1s complement and the carry bit (C). The source operand
is not affected. The previous contents of the destination are lost.
Status Bits
N: Set if result is negative, reset if positive.
Z: Set if result is zero, reset otherwise.
C: Set if there is a carry from the MSB of the result, reset otherwise.
Set to 1 if no borrow, reset if borrow.
V: Set if an arithmetic overflow occurs, reset otherwise.
Mode Bits
OSCOFF, CPUOFF, and GIE are not affected.
Example
Two floating point mantissas (24 bits) are subtracted.
LSBs are in R13 and R10, MSBs are in R12 and R9.
SUB.W
R13,R10 ; 16-bit part, LSBs
SUBC.B
R12,R9
; 8-bit part, MSBs
Example
The 16-bit counter pointed to by R13 is subtracted from a 16-bit counter in R10
and R11(MSD).
SUB.B
@R13+,R10
; Subtract LSDs without carry
SUBC.B
@R13,R11
; Subtract MSDs with carry
...
; resulting from the LSDs
Note:
Borrow Implementation
The borrow is treated as a .NOT. carry :
Borrow
Carry bit
Yes
0
No
1
Summary of Contents for MSP430x4xx Family
Page 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Page 2: ......
Page 6: ...vi ...
Page 114: ...3 76 RISC 16 Bit CPU ...
Page 304: ...5 20 FLL Clock Module ...
Page 340: ...7 8 Supply Voltage Supervisor ...
Page 348: ...8 8 16 Bit Hardware Multiplier ...
Page 372: ...9 24 32 Bit Hardware Multiplier ...
Page 400: ...10 28 DMA Controller ...
Page 428: ...13 10 Basic Timer1 ...
Page 466: ...15 24 Timer_A ...
Page 522: ...17 30 USART Peripheral Interface UART Mode ...
Page 544: ...18 22 USART Peripheral Interface SPI Mode ...
Page 672: ...23 12 Comparator_A ...
Page 692: ...24 20 LCD Controller ...
Page 746: ...26 28 ADC12 ...