dsp56800e Freescale Semiconductor, Inc, dsp56800e Datasheet - Page 217

• Manufacturer Part Number: dsp56800e
• Description: 16-bit Digital Signal Controller Core
• Manufacturer: Freescale Semiconductor, Inc

For word memory accesses:
6.8.3.2
The modifier register must be programmed a little differently when long-word data is to be accessed. Since
each long-word location in the modulo buffer uses up two word memory locations, the size of the modulo
buffer in words must always be an even number, which means that M01 will always be programmed with
an odd value.
Freescale Semiconductor
16-Bit M01 Register Contents
•
•
Modulo arithmetic is performed on word addresses.
M01 = (size of the buffer in words) – 1.
Configuring for Long Word Accesses
$BFFE
$3FFE
$BFFF
$FFFE
$FFFF
$3FFF
$7FFF
$C000
$0000
$0001
$0002
$4000
$8000
$8001
$8002
Table 6-6. Programming the M01 Register—Byte and Word Accesses
The reserved sets of modifier values ($0000, $4000–$8000, and
$C000–$FFFE) must not be used. The behavior of the modulo arithmetic
unit is undefined for these values and might result in erratic program
execution.
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Address Arithmetic Performed
Address Generation Unit
Linear Arithmetic
Modulo 16383
Modulo 16384
Modulo 16383
Modulo 16384
(Reserved)
(Reserved)
(Reserved)
(Reserved)
(Reserved)
(Reserved)
Modulo 2
Modulo 3
Modulo 2
Modulo 3
NOTE:
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Linear and Modulo Address Arithmetic
Pointer Registers Affected
R0 and R1 pointers
R0 and R1 pointers
R0 and R1 pointers
R0 and R1 pointers
R0 and R1 pointers
R0 pointer only
R0 pointer only
R0 pointer only
R0 pointer only
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