Hardware SHA-256 Accelerator API.
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#define | SHA256_RESULT_BYTES 32 |
| | Size of a sha256 result in bytes.
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Hardware SHA-256 Accelerator API.
RP2350 is equipped with an implementation of the SHA-256 hash algorithm. The hardware should first be configured by calling the sha256_set_dma_size and sha256_set_bswap functions. To generate a new hash the hardware should first be initialised by calling sha256_start. The hardware is ready to accept data when sha256_is_ready returns true, at which point the data to be hashed can be written to the address returned by sha256_get_write_addr. The hardware requires 64 bytes to be written in one go or else sha256_err_not_ready will indicate an error and the hashing process must be restarted. sha256_is_sum_valid will return true when there is a valid checksum result which can be retrieved by calling sha256_get_result.
◆ sha256_endianness
SHA-256 endianness definition used in the API.
| Enumerator |
|---|
| SHA256_LITTLE_ENDIAN | Little Endian.
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| SHA256_BIG_ENDIAN | Big Endian.
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◆ sha256_err_not_ready()
| static bool sha256_err_not_ready |
( |
void |
| ) |
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inlinestatic |
Check if data was written before the hardware was ready.
Indicates if an error has occurred due to data being written when the hardware is not ready.
- Returns
- True if data was written before the hardware was ready
◆ sha256_err_not_ready_clear()
| static void sha256_err_not_ready_clear |
( |
void |
| ) |
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inlinestatic |
Clear the "not ready" error condition.
Resets the hardware if a "not ready" error condition is indicated.
◆ sha256_get_result()
Get the checksum result.
Read the 32 byte result calculated by the hardware. Only valid if sha256_is_sum_valid is True
- Parameters
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Copyright (c) 2024 Raspberry Pi (Trading) Ltd.
SPDX-License-Identifier: BSD-3-Clause
◆ sha256_get_write_addr()
| static volatile void * sha256_get_write_addr |
( |
void |
| ) |
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inlinestatic |
Address to write the data to be hashed.
Returns the hardware address where data to be hashed should be written
- Returns
- Address to write data to be hashed
◆ sha256_is_ready()
| static bool sha256_is_ready |
( |
void |
| ) |
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inlinestatic |
Check if a the hardware is ready to accept more data.
After writing 64 bytes of data to the hardware, it will be unable to accept more data for a time. Call this to check if the hardware is ready for more data to be written.
- See also
- sha256_err_not_ready
- Returns
- True if the hardware is ready to receive more data
◆ sha256_is_sum_valid()
| static bool sha256_is_sum_valid |
( |
void |
| ) |
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inlinestatic |
Check if a valid checksum has been calculated.
The checksum result will be invalid when data is first written to the hardware, and then once 64 bytes of data has been written it may take some time to complete the digest of the current block. This function can be used to determine when the checksum is valid.
- Returns
- True if sha256_get_result would return a valid result
◆ sha256_put_byte()
| static void sha256_put_byte |
( |
uint8_t |
b | ) |
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inlinestatic |
Write one byte of data to the SHA-256 hardware.
- Parameters
-
◆ sha256_put_word()
| static void sha256_put_word |
( |
uint32_t |
word | ) |
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inlinestatic |
Write one 32bit word of data to the SHA-256 hardware.
- Parameters
-
◆ sha256_set_bswap()
| static void sha256_set_bswap |
( |
bool |
swap | ) |
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inlinestatic |
Enable or disable byte swapping of 32-bit values.
The SHA256 algorithm expects bytes in big endian order, but the system bus deals with little endian data, so control is provided to convert little endian bus data to big endian internal data. This defaults to true
- Parameters
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| swap | false to disable byte swapping |
◆ sha256_set_dma_size()
| static void sha256_set_dma_size |
( |
uint |
size_in_bytes | ) |
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inlinestatic |
Configure the correct DMA data size.
This must be configured before the DMA channel is triggered and ensures the correct number of transfers is requested per block.
- Parameters
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| size_in_bytes | Size of DMA transfers, either 1, 2 or 4 bytes only. |
◆ sha256_start()
| static void sha256_start |
( |
void |
| ) |
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inlinestatic |
Prepare the hardware for a new checksum.
Called to initialise the hardware before starting the checksum calculation
◆ sha256_wait_ready_blocking()
| static void sha256_wait_ready_blocking |
( |
void |
| ) |
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inlinestatic |
Wait until the hardware is ready to accept more data.
Before writing to the hardware, it's necessary to check it is ready to accept more data. This function waits until the hardware is ready to accept more data
◆ sha256_wait_valid_blocking()
| static void sha256_wait_valid_blocking |
( |
void |
| ) |
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inlinestatic |
Wait until the checksum is valid.
When a multiple of 64 bytes of data has been written to the hardware, the checksum will be valid once the digest of the current block is complete. This function waits until when the checksum result is valid.
v2.0.0