From 44c2d2d5e5ce43563a4912b2967cdb6b2039b6dd Mon Sep 17 00:00:00 2001 From: Josh Rahm Date: Wed, 18 Nov 2020 01:32:24 -0700 Subject: A basic blink program that works off of interrupts. - The init() function renamed to on_reset() - on_reset() now responsible for tight-looping at the end - on_reset() now set the VTable offset to the base of the FLASH - included exhaustive list of irqs in isrs.i - interrupt routines by default flash a code indicating their isr number. - interrupt routines are weak-linked allowing the programmer to override them at-will. --- 02-usart/src/init.c | 45 +++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 45 insertions(+) create mode 100644 02-usart/src/init.c (limited to '02-usart/src/init.c') diff --git a/02-usart/src/init.c b/02-usart/src/init.c new file mode 100644 index 0000000..70703aa --- /dev/null +++ b/02-usart/src/init.c @@ -0,0 +1,45 @@ +#include "arch.h" +#include "system.h" + +/* Forward-declare the main function. This is implemented in main.c. */ +void main(); + +/* These are defined in the linker script. */ +extern uint32_t INIT_DATA_VALUES; +extern uint32_t DATA_SEGMENT_START; +extern uint32_t DATA_SEGMENT_STOP; +extern uint32_t BSS_START; +extern uint32_t BSS_END; + +/* + * Runs before main. Initializes the data and bss segments by loading them + * into memory. + */ +_Noreturn void on_reset() +{ + uint32_t* src; + uint32_t* dest; + + src = &INIT_DATA_VALUES; + dest = &DATA_SEGMENT_START; + + /* Copy the values from flash into the data segment. */ + while (dest != &DATA_SEGMENT_STOP) { + *(dest++) = *(src++); + } + + /* Everything in the BSS segment is set to zero. */ + dest = &BSS_START; + while (dest != &BSS_END) { + *(dest++) = 0; + } + + /* Set the vector offset table to be at the start + * of FLASH memory. */ + SCB.vto_r = 0x08000000; + + /* Jump to main. */ + main(); + + for(;;); +} -- cgit