startup_gcc.c

/*
* Copyright (c) 2012, Mauro Scomparin
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*     * Redistributions of source code must retain the above copyright
*       notice, this list of conditions and the following disclaimer.
*     * Redistributions in binary form must reproduce the above copyright
*       notice, this list of conditions and the following disclaimer in the
*       documentation and/or other materials provided with the distribution.
*     * Neither the name of Mauro Scomparin nor the
*       names of its contributors may be used to endorse or promote products
*       derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY Mauro Scomparin ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL Mauro Scomparin BE LIABLE FOR ANY
* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* File:			LM4F_startup.c.
* Author:		Mauro Scomparin <http://scompoprojects.worpress.com>.
* Version:		1.0.0.
* Description:	LM4F120H5QR startup code.
*/

//-----------------------------------------------------------------------------
// 							 Functions declarations
//-----------------------------------------------------------------------------

// Main should be defined on your main file so it's extern.
extern int main(void);
// rst_handler contains the code to run on reset.
void rst_handler(void);
// nmi_handler it's the code for an non maskerable interrupt.
void nmi_handler(void);
// this is just the default handler.
void empty_def_handler(void);
// this is the code for an hard fault.
void hardfault_handler(void);

extern void UARTStdioIntHandler(void);
extern void SysTickIntHandler(void);
extern void GPIOPortEIntHandler(void);

extern void __libc_init_array(void);
extern void __libc_fini_array(void);

//-----------------------------------------------------------------------------
// 						     Variables declarations
//-----------------------------------------------------------------------------

// defined by the linker it's the stack top variable (End of ram)
extern unsigned long _stack_top;
// defined by the liker, this are just start and end marker for each section.
// .text (code)
extern unsigned long _start_text;
extern unsigned long _end_text;
// .data (data to be copied on ram)
extern unsigned long __data_start;
extern unsigned long __data_end;
// .bss (uninitialized data to set to 0);
extern unsigned long _start_bss;
extern unsigned long _end_bss;

// NVIC ISR table
// the funny looking void(* myvectors[])(void) basically it's a way to make cc accept an array of function pointers.
__attribute__ ((section(".nvic_table")))
void(* myvectors[])(void) = {
	// This are the fixed priority interrupts and the stack pointer loaded at startup at R13 (SP).
	//												VECTOR N (Check Datasheet)
	// here the compiler it's boring.. have to figure that out
    (void (*)) &_stack_top, 
    						// stack pointer should be 
							// placed here at startup.			0
    rst_handler,			// code entry point					1
    nmi_handler,			// NMI handler.						2
    hardfault_handler,		// hard fault handler.				3
    // Configurable priority interruts handler start here.
    empty_def_handler,		// Memory Management Fault			4
    empty_def_handler,		// Bus Fault						5
    empty_def_handler,		// Usage Fault 						6
    0,						// Reserved							7
    0,						// Reserved							8
    0,						// Reserved							9
    0,						// Reserved							10
    empty_def_handler,		// SV call							11
    empty_def_handler,		// Debug monitor					12
    0,						// Reserved							13
    empty_def_handler,		// PendSV							14
    SysTickIntHandler,		// SysTick							15
    // Peripherial interrupts start here.
	empty_def_handler,		// GPIO Port A						16
	empty_def_handler,		// GPIO Port B						17
	empty_def_handler,		// GPIO Port C						18
	empty_def_handler,		// GPIO Port D						19
	GPIOPortEIntHandler,		// GPIO Port E						20
	UARTStdioIntHandler,		// UART 0							21
	empty_def_handler,		// UART 1							22
	empty_def_handler,		// SSI 0							23
	empty_def_handler,		// I2C 0							24
	0,						// Reserved							25
	0,						// Reserved							26
	0,						// Reserved							27
	0,						// Reserved							28
	0,						// Reserved							29
	empty_def_handler,		// ADC 0 Seq 0						30
	empty_def_handler,		// ADC 0 Seq 1						31
	empty_def_handler,		// ADC 0 Seq 2						32
	empty_def_handler,		// ADC 0 Seq 3						33
	empty_def_handler,		// WDT 0 and 1						34
	empty_def_handler,		// 16/32 bit timer 0 A				35
	empty_def_handler,		// 16/32 bit timer 0 B				36
	empty_def_handler,		// 16/32 bit timer 1 A				37
	empty_def_handler,		// 16/32 bit timer 1 B				38
	empty_def_handler,		// 16/32 bit timer 2 A				39
	empty_def_handler,		// 16/32 bit timer 2 B				40
	empty_def_handler,		// Analog comparator 0				41
	empty_def_handler,		// Analog comparator 1				42
	0,						// Reserved							43
	empty_def_handler,		// System control					44
	empty_def_handler,		// Flash + EEPROM control			45
	empty_def_handler,		// GPIO Port F						46
	0,						// Reserved							47
	0,						// Reserved							48
	empty_def_handler,		// UART 2							49
	empty_def_handler,		// SSI 1							50
	empty_def_handler,		// 16/32 bit timer 3 A				51
	empty_def_handler,		// 16/32 bit timer 3 B				52
	empty_def_handler,		// I2C 1							53
	0,						// Reserved							54
	empty_def_handler,		// CAN 0							55
	0,						// Reserved							56
	0,						// Reserved							57
	0,						// Reserved							58
	empty_def_handler,		// Hibernation module				59
	empty_def_handler,		// USB								60
	0,						// Reserved							61
	empty_def_handler,		// UDMA SW							62
	empty_def_handler,		// UDMA Error						63
	empty_def_handler,		// ADC 1 Seq 0						64
	empty_def_handler,		// ADC 1 Seq 1						65
	empty_def_handler,		// ADC 1 Seq 2						66
	empty_def_handler,		// ADC 1 Seq 3						67
	0,						// Reserved							68
	0,						// Reserved							69
	0,						// Reserved							70
	0,						// Reserved							71
	0,						// Reserved							72
	empty_def_handler,		// SSI 2							73
	empty_def_handler,		// SSI 2							74
	empty_def_handler,		// UART 3							75
	empty_def_handler,		// UART 4							76
	empty_def_handler,		// UART 5							77
	empty_def_handler,		// UART 6							78
	empty_def_handler,		// UART 7							79
	0,						// Reserved							80
	0,						// Reserved							81
	0,						// Reserved							82
	0,						// Reserved							83
	empty_def_handler,		// I2C 2							84
	empty_def_handler,		// I2C 4							85
	empty_def_handler,		// 16/32 bit timer 4 A				86
	empty_def_handler,		// 16/32 bit timer 4 B				87
	0,						// Reserved							88
	0,						// Reserved							89
	0,						// Reserved							90
	0,						// Reserved							91
	0,						// Reserved							92
	0,						// Reserved							93
	0,						// Reserved							94
	0,						// Reserved							95
	0,						// Reserved							96
	0,						// Reserved							97
	0,						// Reserved							98
	0,						// Reserved							99
	0,						// Reserved							100
	0,						// Reserved							101
	0,						// Reserved							102
	0,						// Reserved							103
	0,						// Reserved							104
	0,						// Reserved							105
	0,						// Reserved							106
	0,						// Reserved							107
	empty_def_handler,		// 16/32 bit timer 5 A				108
	empty_def_handler,		// 16/32 bit timer 5 B				109
	empty_def_handler,		// 32/64 bit timer 0 A				110
	empty_def_handler,		// 32/64 bit timer 0 B				111
	empty_def_handler,		// 32/64 bit timer 1 A				112
	empty_def_handler,		// 32/64 bit timer 1 B				113
	empty_def_handler,		// 32/64 bit timer 2 A				114
	empty_def_handler,		// 32/64 bit timer 2 B				115
	empty_def_handler,		// 32/64 bit timer 3 A				116
	empty_def_handler,		// 32/64 bit timer 3 B				117
	empty_def_handler,		// 32/64 bit timer 4 A				118
	empty_def_handler,		// 32/64 bit timer 4 B				119
	empty_def_handler,		// 32/64 bit timer 5 A				120
	empty_def_handler,		// 32/64 bit timer 5 B				121
	empty_def_handler,		// System Exception					122
	0,						// Reserved							123
	0,						// Reserved							124
	0,						// Reserved							125
	0,						// Reserved							126
	0,						// Reserved							127
	0,						// Reserved							128
	0,						// Reserved							129
	0,						// Reserved							130
	0,						// Reserved							131
	0,						// Reserved							132
	0,						// Reserved							133
	0,						// Reserved							134
	0,						// Reserved							135
	0,						// Reserved							136
	0,						// Reserved							137
	0,						// Reserved							138
	0,						// Reserved							139
	0,						// Reserved							140
	0,						// Reserved							141
	0,						// Reserved							142
	0,						// Reserved							143
	0,						// Reserved							144
	0,						// Reserved							145
	0,						// Reserved							146
	0,						// Reserved							147
	0,						// Reserved							148
	0,						// Reserved							149
	0,						// Reserved							150
	0,						// Reserved							151
	0,						// Reserved							152
	0,						// Reserved							153
	0						// Reserved							154
};

//-----------------------------------------------------------------------------
// 							Function implementations.
//-----------------------------------------------------------------------------

/* 
* System on reset code. NVIC 1
* Here I prepare the memory for the c compiler.
* The stack pointer should be set at the beginning with the NVIC table already.
* Copy the .data segment from flash into ram.
* 0 to the .bss segment 
*/
	
void rst_handler(void){	
	// Copy the .data section pointers to ram from flash.
	// Look at LD manual (Optional Section Attributes).
	
	// source and destination pointers
	unsigned long *src;
	unsigned long *dest;
	
	//this should be good!
	src = &_end_text;
	dest = &__data_start;
	
	//this too
    while(dest < &__data_end)
    {
        *dest++ = *src++;
    }
	
    // now set the .bss segment to 0!
    dest = &_start_bss;
	while(dest < &_end_bss){
		*dest++ = 0;
	}

	__libc_init_array();
	
	// after setting copying .data to ram and "zero-ing" .bss we are good
	// to start the main() method!
	// There you go!
	main();

	__libc_fini_array();
}

// NMI Exception handler code NVIC 2
void nmi_handler(void){
	// Just loop forever, so if you want to debug the processor it's running.
    while(1){
    }
}

// Hard fault handler code NVIC 3
void hardfault_handler(void){
	// Just loop forever, so if you want to debug the processor it's running.
    while(1){
    }
}

// Empty handler used as default.
void empty_def_handler(void){
	// Just loop forever, so if you want to debug the processor it's running.
    while(1){
    }
}