Use case: suspend/resume mode ¶

Sequence diagram ¶

Suspend/resume mode

@startuml

participant "Application" as App
participant "CRYP" as CRYP

note over App,CRYP: CRYP initialization
App -> CRYP: HAL_CRYP_Init()

note over App,CRYP: Low priority block Encryption
App -> CRYP: HAL_CRYP_Encrypt_IT()

note over App,CRYP: Low priority process suspending
App -> CRYP: HAL_CRYP_ProcessSuspend()

App -> CRYP: HAL_CRYP_Suspend()

note over App,CRYP: High priority process starting
App -> CRYP: HAL_CRYP_Init()

note over App,CRYP: Decrypt high priority block
App -> CRYP: HAL_CRYP_Decrypt_IT()

note over App,CRYP: Resume low priority block processing
App -> CRYP: HAL_CRYP_Resume()

@enduml

Code snippet ¶

HAL1

HAL2

Thread 1

Thread 2

                     /* Set the CRYP parameters */
hcryp.Instance = AES;

/* Set the CRYP parameters */
hcryp.Init.DataType = CRYP_BYTE_SWAP;
hcryp.Init.KeySize = CRYP_KEYSIZE_128B;
hcryp.Init.pKey     = AESKey128;
hcryp.Init.Algorithm = CRYP_AES_ECB;
HAL_CRYP_Init(&hcryp);

/* Low prio block Encryption */
HAL_CRYP_Encrypt_IT(&hcryp, Plaintext_8, 128, Encryptedtext);

/* request suspension */
HAL_CRYP_ProcessSuspend(&hcryp);

/* Suspend low prio block processing */
HAL_CRYP_Suspend(&hcryp);

/* -- Thread 1 released the AES peripheral and informed Thread 2 ---> */

/* Resume low prio block processing */
HAL_CRYP_Resume(&hcryp);

                     /*  */

/* <--- Thread 2 asks to use the AES peripheral for a high-priority task -- */

/*  High priority block processing  */
/* Set the CRYP parameters */
hcryp.Init.DataType  = CRYP_BIT_SWAP;
hcryp.Init.KeySize   = CRYP_KEYSIZE_256B;
hcryp.Init.pKey      = AESKey256;
hcryp.Init.pInitVect = AESIV;
hcryp.Init.Algorithm = CRYP_AES_CTR;
HAL_CRYP_Init(&hcryp);

/*  Decrypt */
HAL_CRYP_Decrypt_IT(&hcryp, CiphertextAESCTR256_HighPrio,
                                16, Decryptedtext_HighPrio);

/* <--- Thread 1 releases the AES peripheral so that the low-priority task can resume -- */

Thread 1

Thread 2

                      /* Set the AES parameters */
 HAL_AES_Init(&haes,HAL_AES);
 HAL_AES_ECB_SetConfig(&haes);
 HAL_AES_SetDataSwapping(&haes, HAL_AES_DATA_SWAPPING_BYTE);
 HAL_AES_SetNormalKey(&haes, HAL_AES_KEY_SIZE_128BIT, AESKey128);

 /* Low prio block Encryption */
 HAL_AES_Encrypt_IT(&haes, Plaintext_8, 128 , Encryptedtext);

 /* request suspension */
 HAL_AES_RequestSuspend(&haes);

/* --------------------- Wait for suspend callback -------------------*/

 /* Suspend low prio block processing */
 HAL_AES_SaveContext(&haes,&p_context);

 /* -- Thread 1 released the AES peripheral and informed Thread 2 ---> */

 /* Restore process1 context */
 HAL_AES_RestoreContext(&haes, &p_context);

 /* Resume low prio block processing */
 HAL_AES_Resume(&haes);

                     /*  */

/* <--- Thread 2 asks to use the AES peripheral for a high-priority task -- */

/*  High priority block processing  */
/* Set the CRYP parameters */
HAL_AES_CTR_SetConfig(&haes,AESIV);
HAL_AES_SetDataSwapping(&haes, HAL_AES_DATA_SWAPPING_BIT);
HAL_AES_SetNormalKey(&haes, HAL_AES_KEY_SIZE_256BIT, AESKey256);

/*  Decrypt */
HAL_AES_Decrypt_IT(&haes, CiphertextAESCTR256_HighPrio,
                             16, Decryptedtext_HighPrio);

/* --------------------- Wait for decrypt complete callback -------------------*/

/* <--- Thread 1 releases the AES peripheral so that the low-priority task can resume -- */

Key changes ¶

HAL2 provides explicit suspend and context management APIs: HAL_AES_RequestSuspend(), HAL_AES_SaveContext(), and HAL_AES_RestoreContext().
HAL2 splits configuration steps into dedicated functions (for example, HAL_AES_ECB_SetConfig() and HAL_AES_SetNormalKey()).