LaunchScheduler.c

__attribute__((naked)) void LaunchScheduler(void)
{
    /// R0 contains the address of currentPt
    __asm("LDR     R0, =pCurntTcb");
    /// R2 contains the address in currentPt(value of currentPt)
    __asm("LDR     R2, [R0]");
    /// Load the SP reg with the stacked SP value
    __asm("LDR     R4, [R2]");
    __asm("MOV     SP, R4");
    /// Pop registers R8-R11(user saved context)
    __asm("POP     {R4-R7}");
    __asm("MOV     R8, R4");
    __asm("MOV     R9, R5");
    __asm("MOV     R10, R6");
    __asm("MOV     R11, R7");
    /// Pop registers R4-R7(user saved context)
    __asm("POP     {R4-R7}");
    ///  Start poping the stacked exception frame.
    __asm("POP     {R0-R3}");
    __asm("POP     {R4}");
    __asm("MOV     R12, R4");
    /// Skip the saved LR
    __asm("ADD     SP,SP,#4");
    /// POP the saved PC into LR via R4, We do this to jump into the
    /// first task when we execute the branch instruction to exit this routine.
    __asm("POP     {R4}");
    __asm("MOV     LR, R4");
    __asm("ADD     SP,SP,#4");
    /// Enable interrupts
    __asm("CPSIE   I ");
    __asm("BX      LR");
}