SH7713 datasheet(122/904 Pages) RENESAS

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Section 3 DSP Operating Unit

Rev.1.50 Aug. 30, 2006 Page 82 of 860

REJ09B0288-0150

The rule is shown in table 3.3.

Table 3.3

RS and RE Setting Rule

Number of Instructions in Repeat Loop

≥ 4

RptStart0 + 8

RptStart0 + 6

RptStart0 + 4

RptStart

RptStart0 + 4

RptEnd3 + 4

Note:

The terms used above in table 3.3, are defined as follows.

RptStart: Address of the repeat start instruction

RptStart0: Address of the instruction one instruction prior to the repeat start instruction

RptEnd3: Address of the instruction three instructions prior to the repeat end instruction

Repeat Control Instructions and Repeat Control Macros: To describe a repeat loop, the RS

and RE registers must be specified appropriately by the LDRS and LDRS instructions and then the

number of repetitions must be specified by the SERTC instruction. An 8-bit immediate data or a

general register can be used as an operand of the SETRC instruction. To specify the RC as a value

greater than 256, use SETRC Rm type instructions.

Table 3.4

Repeat Control Instructions

Instruction

Operation

Number of

Execution States

LDRS @(disp,PC)

Calculates (disp x 2 + PC) and stores the result to the

RS register

LDRE @(disp,PC)

Calculates (disp x 2 + PC) and stores the result to the

RE register

SETRC #imm

Sets 8-bit immediate data imm to the RC[11:0] bits of

the SR register and sets the information related to the

number of repetitions to the RF[1:0] bits of the SR.

RC[11:0] can be specified as 0 to 255.

SETRC Rm

Sets the[11:0] bits of the Rm register to the RC[11:0]

bits of the SR register and sets the information related

to the number of repetitions to the RF[1:0] bits of the

SR.

RC[11:0] can be specified as 0 to 4095.

The RS and RE registers must be specified appropriately according to the rules shown in table 3.3.

The SH assembler supports control macros (REPEAT) as shown in table 3.5 to solve problems.

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