Motorola DSP56000, 24-Bit Digital Signal Processor manual Jump to Subroutine if Bit Clear, Example

INSTRUCTION DESCRIPTIONS

JSCLR

Jump to Subroutine if Bit Clear

JSCLR

specified in the effective address field is always updated independently of the state of the nth bit. All address register indirect addressing modes may be used to reference the source operand S. Absolute short and I/O short addressing modes may also be used.

Restrictions: A JSCLR instruction used within a DO loop cannot specify the loop address (LA) as its target.

A JSCLR located at LA, LA–1, or LA–2 of a DO loop, cannot specify the program control- ler registers SR, SP, SSH, SSL, LA, or LC as its target.

JSCLR SSH or JSCLR SSL cannot follow an instruction that changes the SP.

A JSCLR instruction cannot be repeated using the REP instruction.

Example:

:

JSCLR #$1,Y:<<$FFE3,$1357 ;go sub. at P:$1357 if bit 1 in Y:$FFE3 is clear

:

Explanation of Example: In this example, program execution is transferred to the sub-

routine at absolute address P:$1357 in program memory if bit 1 of the external I/O loca- tion Y:<<$FFE3 is a zero. If the specified bit is not clear, no jump is taken and the program counter (PC) is incremented by 1.

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