//---------------------------------------------------------------------------
void ThreadPort_InitStack(Thread_t *pstThread_)
{
// Initialize the stack for a Thread_t
K_USHORT usAddr;
K_UCHAR *pucStack;
K_USHORT i;
// Get the address of the thread's entry function
usAddr = (K_USHORT)(pstThread_->pfEntryPoint);
// Start by finding the bottom of the stack
pucStack = (K_UCHAR*)pstThread_->pwStackTop;
// clear the stack, and initialize it to a known-default value (easier
// to debug when things go sour with stack corruption or overflow)
for (i = 0; i < pstThread_->usStackSize; i++)
{
pstThread_->pwStack[i] = 0xFF;
}
// Our context starts with the entry function
PUSH_TO_STACK(pucStack, (K_UCHAR)(usAddr & 0x00FF));
PUSH_TO_STACK(pucStack, (K_UCHAR)((usAddr >> 8) & 0x00FF));
// R0
PUSH_TO_STACK(pucStack, 0x00); // R0
// Push status register and R1 (which is used as a constant zero)
PUSH_TO_STACK(pucStack, 0x80); // SR
PUSH_TO_STACK(pucStack, 0x00); // R1
// Push other registers
for (i = 2; i <= 23; i++) //R2-R23
{
PUSH_TO_STACK(pucStack, i);
}
// Assume that the argument is the only stack variable
PUSH_TO_STACK(pucStack, (K_UCHAR)(((K_USHORT)(pstThread_->pvArg)) & 0x00FF)); //R24
PUSH_TO_STACK(pucStack, (K_UCHAR)((((K_USHORT)(pstThread_->pvArg))>>8) & 0x00FF)); //R25
// Push the rest of the registers in the context
for (i = 26; i <=31; i++)
{
PUSH_TO_STACK(pucStack, i);
}
// Set the top o' the stack.
pstThread_->pwStackTop = (K_UCHAR*)pucStack;
// That's it! the thread is ready to run now.
}
void push_nav(QSP_ARG_DECL Gen_Win *gwp)
{
Gen_Win *current_gwp;
// We can push a viewer or anything!?
//assert( GW_TYPE(NAVP_GW(np_p)) == GW_NAV_PANEL );
if( nav_stack == NULL )
nav_stack = new_stack();
// We need to keep a stack of panels...
if( (current_gwp=TOP_OF_STACK(nav_stack)) != NULL ){
unshow_genwin(QSP_ARG current_gwp);
}
PUSH_TO_STACK(nav_stack,gwp);
//fprintf(stderr,"showing associated panel %s\n",PO_NAME(NAVP_PANEL(gwp)));
show_genwin(QSP_ARG gwp);
}
/*
1) Setting up the Thread_t stacks
Stack consists of 2 separate frames mashed together.
a) Exception Stack Frame
Contains the 8 registers the CPU pushes/pops to/from the stack on execution
of an exception:
[ XPSR ]
[ PC ]
[ LR ]
[ R12 ]
[ R3 ]
[ R2 ]
[ R1 ]
[ R0 ]
XPSR - Needs to be set to 0x01000000; the "T" bit (thumb) must be set for
any Thread_t executing on an ARMv6-m processor
PC - Should be set with the initial entry point for the Thread_t
LR - The base link register. We can leave this as 0, and set to 0xD on
first context switch to tell the CPU to resume execution using the
stack pointer held in the PSP as the regular stack.
This is done by the CPU automagically- this format is part of the
architecture, and there's nothing we can do to change or modify it.
b) "Other" Register Context
[ R11 ]
...
[ R4 ]
These are the other GP registers that need to be backed up/restored on a
context switch, but aren't by default on a CM0 exception. If there were
any additional hardware registers to back up, then we'd also have to
include them in this part of the context.
These all need to be manually pushed to the stack on stack creation, and
puhsed/pop as part of a normal context switch.
*/
void ThreadPort_InitStack(Thread_t *pclThread_)
{
K_ULONG *pulStack;
K_ULONG *pulTemp;
K_ULONG ulAddr;
K_USHORT i;
// Get the entrypoint for the Thread_t
ulAddr = (K_ULONG)(pclThread_->pfEntryPoint);
// Get the top-of-stack pointer for the Thread_t
pulStack = (K_ULONG*)pclThread_->pwStackTop;
// Initialize the stack to all FF's to aid in stack depth checking
pulTemp = (K_ULONG*)pclThread_->pwStack;
for (i = 0; i < pclThread_->usStackSize / sizeof(K_ULONG); i++)
{
pulTemp[i] = 0xFFFFFFFF;
}
PUSH_TO_STACK(pulStack, 0); // We need one word of padding, apparently...
//-- Simulated Exception Stack Frame --
PUSH_TO_STACK(pulStack, 0x01000000); // XSPR
PUSH_TO_STACK(pulStack, ulAddr); // PC
PUSH_TO_STACK(pulStack, 0); // LR
PUSH_TO_STACK(pulStack, 0x12);
PUSH_TO_STACK(pulStack, 0x3);
PUSH_TO_STACK(pulStack, 0x2);
PUSH_TO_STACK(pulStack, 0x1);
PUSH_TO_STACK(pulStack, (K_ULONG)pclThread_->pvArg); // R0 = argument
//-- Simulated Manually-Stacked Registers --
PUSH_TO_STACK(pulStack, 0x11);
PUSH_TO_STACK(pulStack, 0x10);
PUSH_TO_STACK(pulStack, 0x09);
PUSH_TO_STACK(pulStack, 0x08);
PUSH_TO_STACK(pulStack, 0x07);
PUSH_TO_STACK(pulStack, 0x06);
PUSH_TO_STACK(pulStack, 0x05);
PUSH_TO_STACK(pulStack, 0x04);
pulStack++;
pclThread_->pwStackTop = pulStack;
}
