exception.c

#include "exception.h"
#include "csr.h"
#include "serial.h"
#include "assert.h"

//-----------------------------------------------------------------
// Locals
//-----------------------------------------------------------------
#define CAUSE_MAX_EXC      (CAUSE_PAGE_FAULT_STORE + 1)
static fp_exception        _exception_table[CAUSE_MAX_EXC];

static fp_irq              _irq_handler     = 0;

void exception_set_irq_handler(fp_irq handler)         { _irq_handler = handler; }
void exception_set_syscall_handler(fp_syscall handler) 
{ 
    _exception_table[CAUSE_ECALL_U] = handler;
    _exception_table[CAUSE_ECALL_S] = handler;
    _exception_table[CAUSE_ECALL_M] = handler;
}
//-----------------------------------------------------------------
// exception_set_handler: Register exception handler
//-----------------------------------------------------------------
void exception_set_handler(int cause, fp_exception handler)
{
    _exception_table[cause] = handler;
}
//-----------------------------------------------------------------
// exception_handler:
//-----------------------------------------------------------------
struct irq_context * exception_handler(struct irq_context *ctx)
{
    // External interrupt
    if (ctx->cause & CAUSE_INTERRUPT)
    {
        if (_irq_handler)
            ctx = _irq_handler(ctx);
        else
            serial_putstr_hex("ERROR: Unhandled IRQ: ", ctx->cause);
    }
    // Exception
    else
    {
        switch (ctx->cause)
        {
            case CAUSE_ECALL_U:
            case CAUSE_ECALL_S:
            case CAUSE_ECALL_M:
                ctx->pc += 4;
                break;
        }

        if (ctx->cause < CAUSE_MAX_EXC && _exception_table[ctx->cause])
            ctx = _exception_table[ctx->cause](ctx);
        else
        {
            serial_putstr_hex("ERROR: Unhandled exception: ", ctx->cause);
            serial_putstr_hex("       at PC: ", ctx->pc);
            assert(!"Unhandled exception");
        }
    }
    return ctx;
}