Datasheet

Instruction Set Description www.ti.com
4.6.3.32 SUBX
SUBX.A Subtract source address-word from destination address-word
SUBX.[W] Subtract source word from destination word
SUBX.B Subtract source byte from destination byte
SUBX.A src,dst
Syntax
SUBX src,dst or SUBX.W src,dst
SUBX.B src,dst
Operation (.not. src) + 1 + dst → dst or dst – src → dst
Description The source operand is subtracted from the destination operand. This is done by adding
the 1s complement of the source + 1 to the destination. The source operand is not
affected. The result is written to the destination operand. Both operands may be located
in the full address space.
Status Bits N: Set if result is negative (src > dst), reset if positive (src ≤ dst)
Z: Set if result is zero (src = dst), reset otherwise (src ≠ dst)
C: Set if there is a carry from the MSB, reset otherwise
V: Set if the subtraction of a negative source operand from a positive destination
operand delivers a negative result, or if the subtraction of a positive source operand
from a negative destination operand delivers a positive result, reset otherwise (no
overflow)
Mode Bits OSCOFF, CPUOFF, and GIE are not affected.
Example A 20-bit constant 87654h is subtracted from EDE (LSBs) and EDE+2 (MSBs).
SUBX.A #87654h,EDE ; Subtract 87654h from EDE+2|EDE
Example A table word pointed to by R5 (20-bit address) is subtracted from R7. Jump to label
TONI if R7 contains zero after the instruction. R5 is auto-incremented by two. R7.19:16 =
0.
SUBX.W @R5+,R7 ; Subtract table number from R7. R5 + 2
JZ TONI ; R7 = @R5 (before subtraction)
... ; R7 <> @R5 (before subtraction)
Example Byte CNT is subtracted from the byte R12 points to in the full address space. Address of
CNT is within PC ± 512 K.
SUBX.B CNT,0(R12) ; Subtract CNT from @R12
Note: Use SUBA for the following two cases for better density and execution.
SUBX.A Rsrc,Rdst
SUBX.A #imm20,Rdst
250
CPUX SLAU144J–December 2004–Revised July 2013
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