Cortex-M3 HAL interrupt-priority code bug

[Nagaraj K]

Hi,
   I was browsing through the Cortex-M3 HAL port and everything looks
OK except for the function
hal_interrupt_set_level() in hal\cortexm\arch\current\src\hal_misc.c

Here is the original function.

__externC void hal_interrupt_set_level( cyg_uint32 vector, cyg_uint32 level )
{
    cyg_uint32 l = (level)+CYGNUM_HAL_CORTEXM_PRIORITY_MAX;
    if( l > 0xFF ) l = 0xFF; /* clamp to 0xFF */
    if( vector >= CYGNUM_HAL_INTERRUPT_EXTERNAL &&
        vector <= CYGNUM_HAL_INTERRUPT_NVIC_MAX )
    {
        HAL_WRITE_UINT8(
CYGARC_REG_NVIC_BASE+CYGARC_REG_NVIC_PR(vector-CYGNUM_HAL_INTERRUPT_EXTERNAL),
                         l );
    }
    else if ( vector == CYGNUM_HAL_INTERRUPT_SYS_TICK )
    {
        cyg_uint32 shpr2;
        HAL_READ_UINT32( CYGARC_REG_NVIC_BASE+CYGARC_REG_NVIC_SHPR2, shpr2 );
        shpr2 &= ~0xFF000000;
        shpr2 |= (l)<<24;
        HAL_WRITE_UINT32( CYGARC_REG_NVIC_BASE+CYGARC_REG_NVIC_SHPR2, shpr2 );
    }
    HAL_VAR_INTERRUPT_SET_LEVEL( vector, level );
}

I see that this function wrongly implements the priority level in
Cortex-M3 processor. According to the Cortex-M3 data sheet, we need to
write the priority level to the top N bits of the register where N is
the number of priority level bits implemented in this particular
version of the cortex variant. Hence I feel that the right
implementation should be

__externC void hal_interrupt_set_level( cyg_uint32 vector, cyg_uint32 level )
{
    cyg_uint32 l = (level)<<(8-CYGNUM_HAL_CORTEXM_PRIORITY_LEVEL_BITS);
    if( l > 0xFF ) l = 0xFF; /* clamp to 0xFF */
    if( vector >= CYGNUM_HAL_INTERRUPT_EXTERNAL &&
        vector <= CYGNUM_HAL_INTERRUPT_NVIC_MAX )
    {
        HAL_WRITE_UINT8(
CYGARC_REG_NVIC_BASE+CYGARC_REG_NVIC_PR(vector-CYGNUM_HAL_INTERRUPT_EXTERNAL),
                         l );
    }
    else if ( vector == CYGNUM_HAL_INTERRUPT_SYS_TICK )
    {
        cyg_uint32 shpr2;
        HAL_READ_UINT32( CYGARC_REG_NVIC_BASE+CYGARC_REG_NVIC_SHPR2, shpr2 );
        shpr2 &= ~0xFF000000;
        shpr2 |= (level)<<24;
        HAL_WRITE_UINT32( CYGARC_REG_NVIC_BASE+CYGARC_REG_NVIC_SHPR2, shpr2 );
    }
    HAL_VAR_INTERRUPT_SET_LEVEL( vector, level );
}

I am new to this developer forum and I am sorry if this is not the
right mailing list for this discussion. If so, please suggest an
alternate forum.

Thanks & Regards, Nagaraj