#include <string.h>
#include <generated/csr.h>

#include "log.h"
#include "mailbox.h"
#include "elf_loader.h"
#include "services.h"
#include "kloader.h"


static struct symbol symtab[128];
static int _symtab_count;
static char _symtab_strings[128*16];
static char *_symtab_strptr;

static void symtab_init(void)
{
    memset(symtab, 0, sizeof(symtab));
    _symtab_count = 0;
    _symtab_strptr = _symtab_strings;
}

static int symtab_add(const char *name, void *target)
{
    if(_symtab_count >= sizeof(symtab)/sizeof(symtab[0])) {
        log("Too many provided symbols in object");
        symtab_init();
        return 0;
    }
    symtab[_symtab_count].name = _symtab_strptr;
    symtab[_symtab_count].target = target;
    _symtab_count++;

    while(1) {
        if(_symtab_strptr >= &_symtab_strings[sizeof(_symtab_strings)]) {
            log("Provided symbol string table overflow");
            symtab_init();
            return 0;
        }
        *_symtab_strptr = *name;
        _symtab_strptr++;
        if(*name == 0)
            break;
        name++;
    }

    return 1;
}

int kloader_load(void *buffer, int length)
{
    if(!kernel_cpu_reset_read()) {
        log("BUG: attempted to load while kernel CPU running");
        return 0;
    }
    symtab_init();
    return load_elf(
        resolve_service_symbol, symtab_add,
        buffer, length, (void *)KERNELCPU_PAYLOAD_ADDRESS, 4*1024*1024);
}

kernel_function kloader_find(const char *name)
{
    return find_symbol(symtab, name);
}

extern char _binary_ksupport_bin_start;
extern char _binary_ksupport_bin_end;

static void start_kernel_cpu(void *addr)
{
    memcpy((void *)KERNELCPU_EXEC_ADDRESS, &_binary_ksupport_bin_start,
        &_binary_ksupport_bin_end - &_binary_ksupport_bin_start);
    mailbox_acknowledge();
    mailbox_send(addr);
    kernel_cpu_reset_write(0);
}

void kloader_start_bridge(void)
{
    start_kernel_cpu(NULL);
}

void kloader_start_user_kernel(kernel_function k)
{
    if(!kernel_cpu_reset_read()) {
        log("BUG: attempted to start kernel CPU while already running (user kernel)");
        return;
    }
    start_kernel_cpu((void *)k);
}

void kloader_start_idle_kernel(void)
{
    if(!kernel_cpu_reset_read()) {
        log("BUG: attempted to start kernel CPU while already running (idle kernel)");
        return;
    }
    /* TODO */
}

void kloader_stop_kernel(void)
{
    kernel_cpu_reset_write(1);
}