/* Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 *
 * Implementations of stateful memory operations.
 */

#include "stateful_util.h"

#include "utility.h"

void StatefulInit(MemcpyState* state, void* buf, uint64_t len) {
  state->remaining_buf = buf;
  state->remaining_len = len;
  state->overrun = 0;
}

void* StatefulSkip(MemcpyState* state, uint64_t len) {
  if (state->overrun)
    return NULL;
  if (len > state->remaining_len) {
    state->overrun = 1;
    return NULL;
  }
  state->remaining_buf += len;
  state->remaining_len -= len;
  return state;                         // have to return something non-NULL
}

void* StatefulMemcpy(MemcpyState* state, void* dst,
                     uint64_t len) {
  if (state->overrun)
    return NULL;
  if (len > state->remaining_len) {
    state->overrun = 1;
    return NULL;
  }
  Memcpy(dst, state->remaining_buf, len);
  state->remaining_buf += len;
  state->remaining_len -= len;
  return dst;
}

const void* StatefulMemcpy_r(MemcpyState* state, const void* src,
                             uint64_t len) {
  if (state->overrun)
    return NULL;
  if (len > state->remaining_len) {
    state->overrun = 1;
    return NULL;
  }
  Memcpy(state->remaining_buf, src, len);
  state->remaining_buf += len;
  state->remaining_len -= len;
  return src;
}

const void* StatefulMemset_r(MemcpyState* state, const uint8_t val,
                             uint64_t len) {
  if (state->overrun)
    return NULL;
  if (len > state->remaining_len) {
    state->overrun = 1;
    return NULL;
  }
  Memset(state->remaining_buf, val, len);
  state->remaining_buf += len;
  state->remaining_len -= len;
  return state;                         // have to return something non-NULL
}
