Motorola DSP56800 Manual page 400

TST
Operation:
S - 0 (parallel move)
Description: Compare the specified source accumulator (S) with zero, and set the condition codes accordingly. No
result is stored, although the condition codes are updated.
Example:
TST
Before Execution
8 0203
A2 A1
SR
0300
Explanation of Example:
Prior to execution, the 36-bit A accumulator contains the value $8:0203:0000, and the 16-bit SR con-
tains the value $0300. Execution of the TST A instruction compares the value in the A register with
zero and updates the CCR accordingly. The contents of the A accumulator are not affected.
Condition Codes Affected:
15 14
LF *
See Section 3.6.2, "36-Bit Destinations—CC Bit Set," on page 3-34 and Section 3.6.4, "20-Bit Desti-
nations—CC Bit Set," on page 3-34 for the case when the CC bit is set.
A-170
Test Accumulator
A X:(R0)+N,B
0000
A0
MR
13 12 11 10 9
* * * * I1
SZ — Set according to the standard definition of the SZ bit (parallel move)
L — Set if data limiting has occurred during parallel move
E — Set if the signed integer portion of A or B result is in use
U — Set according to the standard definition of the U bit
N — Set if bit 35 of A or B result is set except during saturation
Z — Set if A or B result equals zero
V — Always cleared
C — Always cleared
DSP56800 Family Manual
Assembler Syntax:
TST S
; set condition codes for the value
; in A, update B and R0
After Execution
8 0203
A2 A1
SR
0338
CCR
8 7 6 5 4
I0 SZ L E U
(parallel move)
0000
A0
3 2 1 0
N Z V C
TST