ST STM32L4 5 Series Reference Manual page 866

Hash processor (HASH)
Bits 11:8 NBW: Number of words already pushed
Bit 18 and bit 7 ALGO[1:0]: Algorithm selection
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This bitfield reflects the number of words in the message that have already been
pushed into the IN FIFO. NBW increments (+1) when a write access is
performed to the HASH_DIN register while DINNE = 1.
It goes to zero when the INIT bit is written to 1 or when a digest calculation starts
(DCAL written to 1 or DMA end of transfer).
If the DMA is not used
0000 and DINNE=0: no word has been pushed into the DIN buffer, i.e. both
HASH_DIN register and IN FIFO are empty.
0000 and DINNE=1: one word has been pushed into the DIN buffer, i.e.
HASH_DIN register contains one word and IN FIFO is empty.
0001: two words have been pushed into the DIN buffer, i.e. HASH_DIN register
and the IN FIFO contain one word each.
...
1111: 16 words have been pushed into the DIN buffer.
If the DMA is used
NBW is the exact number of words that have been pushed into the IN FIFO by
the DMA.
These bits selects the SHA-1, SHA-224, SHA256 or the MD5 algorithm:
00: SHA-1 algorithm selected
01: MD5 algorithm selected
10: SHA224 algorithm selected
11: SHA256 algorithm selected
Note: This selection is only taken into account when the INIT bit is set. Changing
this bit during a computation has no effect.
Bit 6 MODE: Mode selection
This bit selects the HASH or HMAC mode for the selected algorithm:
0: Hash mode selected
1: HMAC mode selected. LKEY must be set if the key being used is longer than
64 bytes.
Note: This selection is only taken into account when the INIT bit is set. Changing
this bit during a computation has no effect.
Bits 5:4 DATATYPE: Data type selection
These bits define the format of the data entered into the HASH_DIN register:
00: 32-bit data. The data written to HASH_DIN are directly used by the hash
processing, without reordering.
01: 16-bit data or half-word. The data written to HASH_DIN are considered as
two half-words, and are swapped before being used by the hash processing.
10: 8-bit data or bytes. The data written to HASH_DIN are considered as four
bytes, and are swapped before being used by the hash processing.
11: bit data or bit-string. The data written to HASH_DIN are considered as 32 bits
(1st bit of the string at position 0), and are swapped before being used by the
hash processing (first bit of the string at position 31).
DocID024597 Rev 5
RM0351