/* Memory access callbacks: data is input/output, return RV_BAD on fault, 0 otherwise */
typedef rv_res (*rv_store_cb)(void *user, rv_u32 addr, rv_u8 data);
typedef rv_res (*rv_load_cb)(void *user, rv_u32 addr, rv_u8 *data);

/* Initialize CPU. */
void rv_init(rv *cpu, void *user, rv_load_cb load_cb, rv_store_cb store_cb);

/* Single-step CPU. Returns 0 on success, one of RV_E* on exception. */
rv_u32 rv_step(rv *cpu);

#include <stdio.h>
#include <string.h>

#include "rv.h"

rv_res load_cb(void *user, rv_u32 addr, rv_u8 *data) {
  if (addr - 0x80000000 > 0x10000) /* Reset vector is 0x80000000 */
    return RV_BAD;
  *data = ((rv_u8 *)(user))[addr - 0x80000000];
  return RV_OK;
}

rv_res store_cb(void *user, rv_u32 addr, rv_u8 data) {
  if (addr - 0x80000000 > 0x10000)
    return RV_BAD;
  ((rv_u8 *)(user))[addr - 0x80000000] = data;
  return RV_OK;
}

rv_u32 program[2] = {
    /* _start: */
    0x02A88893, /* add a7, a7, 42 */
    0x00000073  /* ecall */
};

int main(void) {
  rv_u8 mem[0x10000];
  rv cpu;
  rv_init(&cpu, (void *)mem, &load_cb, &store_cb);
  memcpy((void *)mem, (void *)program, sizeof(program));
  while (rv_step(&cpu) != RV_EECALL) {
  }
  printf("Environment call @ %08X: %u\n", cpu.pc, cpu.r[17]);
  return 0;
}