# SVC_HMACSHA1Update

## Syntax

      #include <twl/os/common/systemCall.h>

      void SVC_HMACSHA1Update( SVCHMACSHA1Context *context,
                                const void* data,
                                u32 len );

## Arguments

context | Pointer to the context structure for HMAC-SHA1 generation.
data | Pointer to the input data.
len | Size of the input data.

## Return Values

None.

## Description

This function updates the HMAC-SHA1 digest value based on the input data.

context must be initialized beforehand with `SVC_HMACSHA1Init()`.

Call this function as many times as needed, and then use the `SVC_HMACSHA1GetHash` function to obtain the digest value. Specify the input data using data and len. Any size and alignment position can be used.

## See Also

`SVC_HMACSHA1Init`, `SVC_HMACSHA1GetHash`, `SVC_SHA1Update`

## Revision History

2007/10/24 Initial version.

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