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Move interrupts to bootloader when IVSEL is set #546

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Move interrupts to bootloader when IVSEL is set #546

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acb73a9
Move the interrupt table to the bootloader sector when IVSEL is set
emanuelen5 Nov 12, 2024
f22aef3
Break out into function
emanuelen5 Nov 15, 2024
b80b39f
Calculate boot size for ATmega328 based on fuses
emanuelen5 Nov 15, 2024
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34 changes: 33 additions & 1 deletion simavr/sim/sim_interrupts.c
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,7 @@
#include "sim_interrupts.h"
#include "sim_avr.h"
#include "sim_core.h"
#include "sim_core_declare.h"

DEFINE_FIFO(avr_int_vector_p, avr_int_pending);

Expand Down Expand Up @@ -226,6 +227,37 @@ avr_interrupt_reti(
table->running[table->running_ptr-1]->vector : 0);
}

static int bootloader_size_avr328(avr_t *avr)
{
const char efuse = avr->fuse[2];
const char bootsz = (efuse >> 1) & 0x3;

switch (bootsz)
{
case 0:
return 256 * 2;
case 1:
return 512 * 2;
case 2:
return 1024 * 2;
default:
return 2048 * 2;
}
}

static int interrupt_table_offset(avr_t *avr)
{
const int mcucr = _SFR_IO8(0x35);
const int ivsel = 1;
const char interrupt_sector_moved_to_bootloader = avr->data[mcucr] & (1 << ivsel);

const int flash_size = avr->flashend + 1;
if (interrupt_sector_moved_to_bootloader)
return flash_size - bootloader_size_avr328(avr);

return 0;
}

/*
* check whether interrupts are pending. If so, check if the interrupt "latency" is reached,
* and if so triggers the handlers and jump to the vector.
Expand Down Expand Up @@ -281,7 +313,7 @@ avr_service_interrupts(
printf("IRQ%d calling\n", vector->vector);
_avr_push_addr(avr, avr->pc);
avr_sreg_set(avr, S_I, 0);
avr->pc = vector->vector * avr->vector_size;
avr->pc = vector->vector * avr->vector_size + interrupt_table_offset(avr);

avr_raise_irq(vector->irq + AVR_INT_IRQ_RUNNING, 1);
avr_raise_irq(table->irq + AVR_INT_IRQ_RUNNING, vector->vector);
Expand Down
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