AURIX™ Forum Discussions

[indra]

Hi, I want to switch to user mode in tc39x. I tried to change the IO bit of psw register but it always setting the interrupt stack control bit(IS) bit. I even tried to change it through an isr in this case the register value isn't changing at all(the isr executes other instructions like toggling gpr value). One reply I got is to change the register value through upper context save area but at that memory location I cant find the psw values. I dont know if I am seeing it correct or wrong . What should I do?

[Jeremy_Zhou]

Hi @indra ,

When an interrupt happens and enters the ISR function, you can try below function to set the PSW in the upper context.

uppercase = _mfcr( CPU_PCI ); //Get the value of the PCI register

pxUpperCSA = portCSA_TO_ADDRESS( uppercase ); //Convert PCXS and PCXO fields in PCXI to CSA addresses pointed by PCX


pxUpperCSA[ 1 ] = pxUpperCSA[ 1 ] & 0xfffff3ffU;   //Set PSW.IO =0

Then exit the ISR function.

BR,

Jeremy

[indra]

Hi @Jeremy_Zhou 

Can you define pxUpperCSA and portCSA to address

BR,

Indra

[Jeremy_Zhou]

Hi @indra ，

/* CSA Manipulation. */
#define portCSA_TO_ADDRESS( pCSA )			( ( uint32_t * )( ( ( ( pCSA ) & 0x000F0000 ) << 12 ) | ( ( ( pCSA ) & 0x0000FFFF ) << 6 ) ) )
#define portADDRESS_TO_CSA( pAddress )		( ( uint32_t )( ( ( ( (uint32_t)( pAddress ) ) & 0xF0000000 ) >> 12 ) | ( ( ( uint32_t )( pAddress ) & 0x003FFFC0 ) >> 6 ) ) )

BR，
Jeremy