Samsung YP-P10 User Manual download pdf (Page 81)

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101

S3C2440A RISC MICROPROCESSOR PROGRAMMER'S MODEL

2-13

Software Interrupt

The Software Interrupt Instruction (SWI) is used for entering Supervisor mode, usually to request a particular

supervisor function. A SWI handler should return by executing the following irrespective of the state (ARM or Thumb):

MOV PC,R14_svc

This restores the PC and CPSR, and returns to the instruction following the SWI.

NOTE

nFIQ, nIRQ, ISYNC, LOCK, BIGEND, and ABORT pins exist only in the ARM920T CPU core.

Undefined Instruction

When ARM920T comes across an instruction which cannot be handled, it takes the undefined instruction trap. This

mechanism may be used to extend either the THUMB or ARM instruction set by software emulation.

After emulating the failed instruction, the trap handler should execute the following irrespective of the state (ARM or

Thumb):

MOVS PC,R14_und

This restores the CPSR and returns to the instruction following the undefined instruction.

Exception Vectors

The following table shows the exception vector addresses.

Table 2-3. Exception Vectors

Address Exception Mode in Entry

0x00000000 Reset Supervisor

0x00000004 Undefined instruction Undefined

0x00000008 Software Interrupt Supervisor

0x0000000C Abort (prefetch) Abort

0x00000010 Abort (data) Abort

0x00000014 Reserved Reserved

0x00000018 IRQ IRQ

0x0000001C FIQ FIQ

1 2 ... 76 77 78 79 80 81 82 83 84 85 86 ... 595 596

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Samsung YP-P10 User Manual Page 81

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