25.1.5.3 Generating an Software Interrupt
If the IT_EN bit is 1 in the SHA_SYSCONFIG register, an interrupt is generated at the completion of the hash by the following steps:
- Receive last block of data (= 64 bytes). (The number of data bytes defined by the SHA_LENGTH register is received in the digest registers, from SHA_ODIGEST_A and SHA_IDIGEST_A to SHA_ODIGEST_H and SHA_IDIGEST_H.
- If required, apply padding to the last block of data.
- Hash the last block of data (80 cycles in SHA-1 mode and 64 cycles in MD5, SHA-224, and SHA-256 modes).
- If required, add an extra 64-byte block of data to complete the padding.
- Hash this extra block of data (80 cycles in SHA-1 mode and 64 cycles in MD5, SHA-224, and SHA-256 modes).
- An interrupt is generated (active low).