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LibrePilot/flight/PiOS/STM32F4xx/startup.c
2012-01-04 19:29:29 -06:00

148 lines
4.4 KiB
C

/**
******************************************************************************
* @addtogroup PIOS PIOS Core hardware abstraction layer
* @{
*
* @file startup.c
* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
* @brief C based startup of F4
* @see The GNU Public License (GPL) Version 3
*
*****************************************************************************/
/*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* for more details.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write to the Free Software Foundation, Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <string.h>
#include <stm32f4xx.h>
/* prototype for main() that tells us not to worry about it possibly returning */
extern int main(void) __attribute__((noreturn));
/* prototype our _main() to avoid prolog/epilog insertion and other related junk */
void _main(void) __attribute__((noreturn, naked, no_instrument_function));
/** default handler for CPU exceptions */
static void default_cpu_handler(void) __attribute__((noreturn, naked, no_instrument_function));
/** BSS symbols XXX should have a header that defines all of these */
extern char _sbss, _ebss;
/** DATA symbols XXX should have a header that defines all of these */
extern char _sidata, _sdata, _edata, _sfast, _efast;
/** The bootstrap/IRQ stack XXX should define size somewhere else */
char irq_stack[1024] __attribute__((section(".irqstack")));
/** exception handler */
typedef const void (vector)(void);
/** CortexM3 CPU vectors */
struct cm3_vectors {
void *initial_stack;
vector *entry;
vector *vectors[14];
};
/**
* Initial startup code.
*/
void
_main(void)
{
// load the stack base for the current stack before we attempt to branch to any function
// that might bounds-check the stack
asm volatile ("mov r10, %0" : : "r" (&irq_stack[0]) : );
/* enable usage, bus and memory faults */
SCB->SHCSR |= SCB_SHCSR_USGFAULTENA_Msk | SCB_SHCSR_BUSFAULTENA_Msk | SCB_SHCSR_MEMFAULTENA_Msk;
/* configure FP state save behaviour - automatic, lazy save */
FPU->FPCCR |= FPU_FPCCR_ASPEN_Msk | FPU_FPCCR_LSPEN_Msk;
/* configure default FPU state */
FPU->FPDSCR |= FPU_FPDSCR_DN_Msk; /* enable Default NaN */
/* enable the FPU */
SCB->CPACR |= (0xf << 20); // turn on CP10/11 for FP support on cores that implement it
/* copy initialised data from flash to RAM */
memcpy(&_sdata, &_sidata, &_edata - &_sdata);
/* zero the BSS */
memset(&_sbss, 0, &_ebss - &_sbss);
/* zero any 'fast' RAM that's been used */
memset(&_sfast, 0, &_efast - &_sfast);
/* fill most of the IRQ/bootstrap stack with a watermark pattern so we can measure how much is used */
/* leave a little space at the top in case memset() isn't a leaf with no locals */
memset(&irq_stack, 0xa5, sizeof(irq_stack) - 64);
/* call main */
(void)main();
}
/**
* Default handler for CPU exceptions.
*/
static void
default_cpu_handler(void)
{
for (;;) ;
}
/** Prototype for optional exception vector handlers */
#define HANDLER(_name) extern vector _name __attribute__((weak, alias("default_cpu_handler")))
/* standard CMSIS vector names */
HANDLER(NMI_Handler);
HANDLER(HardFault_Handler);
HANDLER(MemManage_Handler);
HANDLER(BusFault_Handler);
HANDLER(UsageFault_Handler);
HANDLER(DebugMon_Handler);
/* these vectors point directly to the relevant FreeRTOS functions if they are defined */
HANDLER(vPortSVCHandler);
HANDLER(xPortPendSVHandler);
HANDLER(xPortSysTickHandler);
/** CortexM3 vector table */
struct cm3_vectors cpu_vectors __attribute((section(".cpu_vectors"))) = {
.initial_stack = &irq_stack[sizeof(irq_stack)],
.entry = (vector *)_main,
.vectors = {
NMI_Handler,
HardFault_Handler,
MemManage_Handler,
BusFault_Handler,
UsageFault_Handler,
0,
0,
0,
0,
vPortSVCHandler,
DebugMon_Handler,
0,
xPortPendSVHandler,
xPortSysTickHandler,
}
};
/**
* @}
*/