Motorola DSP56800 Manual page 108

Address Generation Unit
Table 4-9. Programming M01 for Modulo Arithmetic (Continued)
16-Bit M01
Register Contents
$3FFE
$3FFF
$4000
$7FFF
$8000
$8001
$8002
$BFFE
$BFFF
$C000
$FFFE
$FFFF
The high-order two bits of the M01 register determine the arithmetic mode for R0 and R1. A value of 00
for M01[15:14] selects modulo arithmetic for R0. A value of 10 for M01[15:14] selects modulo arithmetic
for both R0 and R1. A value of 11 disables modulo arithmetic. The remaining 14 bits of M01 hold the size
of the buffer minus one.
The reserved values ($0000, $4000-$8000, and $C000-$FFFE) should not
be used. The behavior of the modulo arithmetic unit is undefined for these
values, and may result in erratic program execution.
4-28
Address Arithmetic
Performed
...
Modulo 16383
Modulo 16384
(Reserved)
...
(Reserved)
(Reserved)
Modulo 2
Modulo 3
...
Modulo 16383
Modulo 16384
(Reserved)
...
(Reserved)
Linear Arithmetic
DSP56800 Family Manual
Pointer Registers
...
R0 pointer only
R0 pointer only
...
R0 and R1 pointers
R0 and R1 pointers
...
R0 and R1 pointers
R0 and R1 pointers
...
R0 and R1 pointers both
set up for linear arith-
metic
NOTE:
Affected
...
—
...
—
—
...
—
...
—