Datasheet

Instruction Set Description www.ti.com
4.6.3.9 CMPX
CMPX.A Compare source address-word and destination address-word
CMPX.[W] Compare source word and destination word
CMPX.B Compare source byte and destination byte
CMPX.A src,dst
Syntax
CMPX src,dst or CMPX.W src,dst
CMPX.B src,dst
Operation (.not. src) + 1 + dst or dst – src
Description The source operand is subtracted from the destination operand by adding the 1s
complement of the source + 1 to the destination. The result affects only the status bits.
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 Compare EDE with a 20-bit constant 18000h. Jump to label TONI if EDE equals the
constant.
CMPX.A #018000h,EDE ; Compare EDE with 18000h
JEQ TONI ; EDE contains 18000h
... ; Not equal
Example A table word pointed to by R5 (20-bit address) is compared with R7. Jump to label TONI
if R7 contains a lower, signed, 16-bit number.
CMPX.W @R5,R7 ; Compare two signed numbers
JL TONI ; R7 < @R5
... ; R7 >= @R5
Example A table byte pointed to by R5 (20-bit address) is compared to the input in I/O Port1.
Jump to label TONI if the values are equal. The next table byte is addressed.
CMPX.B @R5+,&P1IN ; Compare P1 bits with table. R5 + 1
JEQ TONI ; Equal contents
... ; Not equal
Note: Use CMPA for the following two cases for better density and execution.
CMPA Rsrc,Rdst
CMPA #imm20,Rdst
224
CPUX SLAU144J–December 2004–Revised July 2013
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