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S3C2501X
INSTRUCTION SET
3-93
3.36 FORMAT 17: SOFTWARE INTERRUPT
[7:0] Comment Field
15
0
1
14
1
0
13
12
11
Value 8
1
7
8
10
9
1
1
1
1
Figure 3-46. Format 17
3.36.1 OPERATION
The SWI instruction performs a software interrupt. On taking the SWI, the processor switches into ARM state and
enters Supervisor (SVC) mode.
The THUMB assembler syntax for this instruction is shown below.
Table 3-24. The SWI Instruction
THUMB Assembler
ARM Equivalent
Action
SWI Value 8
SWI Value 8
Perform Software Interrupt:
Move the address of the next instruction into LR, move CPSR
to SPSR, load the SWI vector address (0x8) into the PC.
Switch to ARM state and enter SVC mode.
NOTE:
Value 8 is used solely by the SWI handler; it is ignored by the processor.
3.36.2 INSTRUCTION CYCLE TIMES
All instructions in this format have an equivalent ARM instruction as shown in Table 3-24. The instruction cycle
times for the THUMB instruction are identical to that of the equivalent ARM instruction.
Examples
SWI 18
; Take the software interrupt exception.
; Enter Supervisor mode with 18 as the
; requested SWI number.
Summary of Contents for S3C2501X
Page 18: ......
Page 275: ...MEMORY CONTROLLER S3C2501X 5 60 NOTES ...
Page 289: ...I2C CONTROLLER S3C2501X 6 14 NOTES ...
Page 373: ...GDMA CONTROLLER S3C2501X 9 24 NOTES ...
Page 435: ...I O PORTS S3C2501X 12 12 NOTES ...