V850ESLASHMA3 datasheet(21/226 Pages) NEC

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CHAPTER 2 REGISTER SET

User’s Manual U14559EJ3V1UM

2.2.4 Program status word (PSW)

The program status word (PSW) is a collection of flags that indicate the status of the program (result of instruction

execution) and the status of the CPU.

If the contents of the bits in this register are modified by the LDSR instruction, the PSW will assume the new value

immediately after the LDSR instruction has been executed. Setting the ID flag to 1, however, will disable interrupt

requests even while the LDSR instruction is being executed.

Bits 31 to 12 and 10 to 8 are reserved for future function expansion (fixed to 0).

Figure 2-6. Program Status Word (PSW) (1/2)

2 1

PSW

Initial value

00000020H

000000

000

Bit Position

Flag Name

Function

Note

Operates with single-step execution when this flag is set to 1 (debug trap occurs each time

instruction is executed).

This flag is cleared to 0 when branching to the interrupt servicing routine.

When the SE bit of the DIR register is 0, this flag is not set (fixed to 0).

Indicates that non-maskable interrupt (NMI) servicing is in progress. This flag is set to 1

when an NMI request is acknowledged, and multiple interrupt servicing is disabled.

0: NMI servicing is not in progress

1: NMI servicing is in progress

Indicates that exception processing is in progress. This flag is set to 1 when an exception

occurs. Even when this bit is set, interrupt requests can be acknowledged.

0: Exception processing is not in progress

1: Exception processing is in progress

Indicates whether a maskable interrupt request can be acknowledged.

0: Interrupts enabled (EI)

1: Interrupts disabled (DI)

SAT

Note

Indicates that an overflow has occurred in a saturated operation and the result is saturated.

This is a cumulative flag. When the result is saturated, the flag is set to 1 and is not cleared

to 0 even if the next result is not saturated. To clear this flag to 0, use the LDSR instruction.

This flag is neither set to 1 nor cleared to 0 by execution of an arithmetic operation

instruction.

0: Not saturated

1: Saturated

Indicates whether a carry or borrow occurred as a result of the operation.

0: Carry or borrow did not occur

1: Carry or borrow occurred

Note

Indicates whether overflow occurred as a result of the operation.

0: Overflow did not occur

1: Overflow occurred

Note Can only be used in type A or B products. Cannot be used in other product types.

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