Motorola DSP56800 Manual page 398

TFR
Operation:
S → D
(parallel move)
Description: Transfer data from the specified source data ALU register (S) to the specified destination data ALU
accumulator (D). The TFR instruction can be used to move the full 36-bit contents of one accumulator
to the other. This transfer occurs with saturation when the saturation bit, SA, is set. The TFR instruction
only affects bits L and SZ bits in the CCR (which can be set by data movement associated with the
instruction's parallel operations).
Usage: This instruction is very similar to a MOVE instruction but has two uses. First, it can be used to perform
a 36-bit transfer of one accumulator to another. Second, when used with a parallel move, this instruc-
tion allows a register move and a memory move to occur simultaneously in 1 instruction that executes
in 1 instruction cycle.
Example:
TFR
Before Execution
3 0123
A2 A1
A CCCC
B2 B1
Explanation of Example:
Prior to execution, the 36-bit A accumulator contains the value $3:0123:0123 and the 36-bit B accu-
mulator contains the value $A:CCCC:EEEE. Execution of the TFR B,A instruction moves the 36-bit
value in B into the 36-bit A accumulator.
Condition Codes Affected:
15 14
LF *
A-168
Transfer Data ALU Register
B,A X:(R0)+,Y1
0123
A0
EEEE
B0
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
DSP56800 Family Manual
Assembler Syntax:
TFR S,D
; move B to A and update Y1, R0
After Execution
A CCCC
A2 A1
A CCCC
B2 B1
CCR
8 7 6 5 4
I0 SZ L E U
(parallel move)
EEEE
A0
EEEE
B0
3 2 1 0
N Z V C
TFR