ARM7TDMI-S Technical Reference Manual(Rev 3)
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2.9.3. Leaving an exception

When an exception is completed, the exception handler must:

  1. Move the LR, minus an offset to the PC. The offset varies according to the type of exception, as shown in Table 2‑3 on page ‑19.

  2. Copy the SPSR back to the CPSR.

  3. Clear the interrupt disable flags that were set on entry.

Note

The action of restoring the CPSR from the SPSR automatically restores the T, F, and I bits to whatever value they held immediately prior to the exception.

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