PDSP1601/PDSP1601A

8

The Register Files

There are two on-chip register files (ALU and Shifter), each

containing two 16 bit registers and each supporting 8

instructions (see Table 4). The instructions for the ALU

register file and the Barrel Shifter Register file are the same.

The Inputs to the register files come from either the ALU or

the Barrel Shifter, and are loaded into the Register files on the

rising edge of CLK.

The register file instructions are latched such that the

instruction will not start executing until the rising edge of the

CLK latches the instruction into the device.

The register file instructions (see Table 4) allow input data

to be loaded into either, neither or both of the registers. Data

is loaded at the end of the cycle in which the instruction is

executing.

The register file instructions allow the output to be sourced

from either of the two registers, the selected output will be valid

during the cycle in which the instruction is executing.

Operation

Load Left Reg Output Right Reg

Load Right Reg Output Left Reg

Load Left Register, Output Left Reg

Load Right Register, Output Right Reg

Load Both Registers, Output Left Reg

No Load Operation, Output Right Reg

No Load Operation, Output Left Reg

No Load Operation, Pass Barrel Shifter Result

Operation

Load Left Reg Output Right Reg

Load Right Reg Output Left Reg

Load Left Register, Output Left Reg

Load Right Register, Output Right Reg

Load Both Registers, Output Left Reg

No Load Operation, Output Right Reg

No Load Operation, Output Left Reg

No Load Operation, Pass ALU Result

Inst

0

1

2

3

4

5

6

7

RA2-RA0

000

001

010

011

100

101

110

111

Mnemonic

LLRRR

LRRLR

LLRLR

LRRRR

LBRLR

NOPRR

NOPLR

NOPPS

ALU REGISTER INSTRUCTIONS

Inst

0

1

2

3

4

5

6

7

RA2-RA0

000

001

010

011

100

101

110

111

Mnemonic

LLRRR

LRRLR

LLRLR

LRRRR

LBRLR

NOPRR

NOPLR

NOPPS

SHIFTER REGISTER INSTRUCTIONS

Table 4 ALU and shift register instructions mnemonics

MNEMONICS

LXXYY

Load XX = Target,

YY

= Source of Output

LBOXX

Load Both Registers, XX

= Source of Output

NOPXX No Load Operation,

XX

= Source of Output