SH7721 datasheet(143/1524 Pages) RENESAS

143 / 1524 page

Section 3 DSP Operating Unit

DSPS301S_010020030200

Rev. 3.00 Jan. 18, 2008 Page 81 of 1458

REJ09B0033-0300

Section 3 DSP Operating Unit

3.1

DSP Extended Functions

This LSI incorporates a DSP unit and X/Y memory directly connected to the DSP unit. This LSI

supports the DSP extended function instruction sets needed to control the DSP unit and X/Y

memory. The DSP extended function instructions are classified into four groups.

(1)

Extended System Control Instructions for the CPU

If the DSP extended function is enabled, the following extended system control instructions can be

used for the CPU.

• Repeat loop control instructions and repeat loop control register access instructions are added.

Looped programs can be executed efficiently by using the zero-overhead repeat control unit.

For details, refer to section 3.3, CPU Extended Instructions.

• Modulo addressing control instructions and control register access instructions are added.

Function allows access to data with a circular structure. For details, refer to section 3.4, DSP

Data Transfer Instructions.

• DSP unit register access instructions are added. Some of the DSP unit registers can be used in

the same way as the CPU system registers. For details, refer to section 3.4, DSP Data Transfer

Instructions.

(2)

Data Transfer Instructions for Data Transfers between DSP Unit and On-Chip X/Y

Memory

Data transfer instructions for data transfers between the DSP unit and on-chip X/Y memory are

called double-data transfer instructions. Instruction codes for these double-transfer instructions are

16 bit codes as well as CPU instruction codes. These data transfer instructions perform data

transfers between the DSP unit and on-chip X/Y memory that is directly connected to the DSP

unit. These data transfer instructions can be described in combination with other DSP unit

operation instructions. For details, refer to section 3.4, DSP Data Transfer Instructions.

(3)

Data Transfer Instructions for Data Transfers between DSP Unit Registers and All

Virtual Address Spaces

Data transfer instructions for data transfers between DSP unit registers and all virtual address

spaces are called single-data transfer instructions. Instruction codes for the double-transfer

instructions are 16 bit codes as well as CPU instruction codes. These data transfer instructions

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