ST STM32F40 Series Reference Manual page 610

RM0090
Bits 31:17 Reserved, forced by hardware to 0.
Bits 15:13 Reserved, forced by hardware to 0.
Bits 11:8 NBW: Number of words already pushed
Bit 16 LKEY: Long key selection
This bit selects between short key (≤ 64 bytes) or long key (> 64 bytes) in HMAC
mode
0: Short key (≤ 64 bytes)
1: Long key (> 64 bytes)
Note: This selection is only taken into account when the INIT bit is set and MODE
= 1. Changing this bit during a computation has no effect.
Bit 12 DINNE: DIN not empty
This bit is set when the HASH_DIN register holds valid data (that is after being
written at least once). It is cleared when either the INIT bit (initialization) or the
DCAL bit (completion of the previous message processing) is written to 1.
0: No data are present in the data input buffer
1: The input buffer contains at least one word of data
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 0000 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 (the buffer is
empty, both the HASH_DIN register and the IN FIFO are empty)
0000 and DINNE=1: 1 word has been pushed into the DIN buffer (The
HASH_DIN register contains 1 word, the IN FIFO is empty)
0001: 2 words have been pushed into the DIN buffer (the HASH_DIN register
and the IN FIFO contain 1 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.
Bit 7 ALGO[1:0]: Algorithm selection
These bits selects the SHA-1 or the MD5 algorithm:
0: SHA-1 algorithm selected
1: MD5 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.
Doc ID 018909 Rev 4
Hash processor (HASH)
610/1422