Register Descriptions; Access To Ubc Control Registers - Hitachi SH7750 series Hardware Manual

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Register Descriptions

The access size must be the same as the control register size. If the sizes are different, a write will

not be effected in a UBC register write operation, and a read operation will return an undefined

value. UBC control register contents cannot be transferred to a floating-point register using a

floating-point memory load instruction.

When a UBC control register is updated, use either of the following methods to make the updated

value valid:

1. Execute an RTE instruction after the memory store instruction that updated the register. The

updated value will be valid from the RTE instruction jump destination onward.

2. Execute instructions requiring 5 states for execution after the memory store instruction that

updated the register. As the SH7750 Series executes two instructions in parallel and a

minimum of 0.5 state is required for execution of one instruction, 11 instructions must be

inserted. The updated value will be valid from the 6th state onward.

Rev. 4.0, 04/00, page 680 of 850

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