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Enhanced Time Processing Unit (eTPU2)
MPC5644A Microcontroller Reference Manual, Rev. 6
942
Freescale Semiconductor
Register size override zero-pads an overridden source to 24-bits (if no sign extension is performed, see
Section 24.5.9.2.9, A-source sign extension
) and affects operation size calculation. When register source
is wider than size override, most significant bits of selected register are not used as A source (zeros are
used instead). When size override is wider than selected register, register value is padded to zeros.When
size override is used with MDU operations, it affects only the operand values, but not the operation size:
MDU operation size is fully determined by the operation definition (fields ALUOP, ALUOPI).
24.5.9.2.9
A-source sign extension
The SEXT microinstruction field forces sign extension of A source according to the size of A operand,
either overridden or not by AS/CE field, according to
size-overridden value, not the original one.
A-source sign is not extended in microinstructions without SEXT field, even if AS/CE field is present.
24.5.9.2.10
ALU/MDU Operation Selection
When field ALUOP is available in microinstruction, enhanced ALU operations shown in
can
be performed, otherwise addition is performed. The ALU operations are defined in
. The MDU operations are defined in
Section 24.5.8.3, MAC and Divide Unit
Table 24-92. AS/CE field A source size override funcionality
Size override
Size of selected register
AS value
1
1
All values are zero-padded to 24 bits
8 bits
8 bits
reg[7:0]
8-bits
16 bits
reg[7:0]
8bits
24 bits
reg[7:0]
16 bits
8 bits
reg[15:0]
16 bits
16 bits
reg[15:0]
16 bits
24 bits
reg[15:0]
Table 24-93. A source Sign Extension
SEXT
Meaning
0
extends sign of A source from its size to 24-bits
1
does not extend sign of A source
Table 24-94. ALU Operation Selection – ALUOP
ALUO
P
Operation
Comment
00000
AS mults BS[7:0]
signed multiplication
00001
AS multu BS[7:0]
unsigned multiplication
00010
AS fmults BS[7:0]
signed fractional multiplication
Summary of Contents for MPC5644A
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Page 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Page 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Page 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Page 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Page 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
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