LXR linux/drivers/media/test-drivers/vidtv/vidtv

   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * The Virtual DVB test driver serves as a reference DVB driver and helps
   4 * validate the existing APIs in the media subsystem. It can also aid
   5 * developers working on userspace applications.
   6 *
   7 * Copyright (C) 2020 Daniel W. S. Almeida
   8 */
   9#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
  10
  11#include <linux/printk.h>
  12#include <linux/ratelimit.h>
  13#include <linux/string.h>
  14#include <linux/types.h>
  15
  16#include "vidtv_common.h"
  17
  18/**
  19 * vidtv_memcpy() - wrapper routine to be used by MPEG-TS
  20 *      generator, in order to avoid going past the
  21 *      output buffer.
  22 * @to: Starting element to where a MPEG-TS packet will
  23 *      be copied.
  24 * @to_offset:  Starting position of the @to buffer to be filled.
  25 * @to_size:    Size of the @to buffer.
  26 * @from:       Starting element of the buffer to be copied.
  27 * @len:        Number of elements to be copy from @from buffer
  28 *      into @to+ @to_offset buffer.
  29 *
  30 * Note:
  31 *      Real digital TV demod drivers should not have memcpy
  32 *      wrappers. We use it here because emulating MPEG-TS
  33 *      generation at kernelspace requires some extra care.
  34 *
  35 * Return:
  36 *      Returns the number of bytes written
  37 */
  38u32 vidtv_memcpy(void *to,
  39                 size_t to_offset,
  40                 size_t to_size,
  41                 const void *from,
  42                 size_t len)
  43{
  44        if (unlikely(to_offset + len > to_size)) {
  45                pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
  46                                   to_offset + len,
  47                                   to_size);
  48                return 0;
  49        }
  50
  51        memcpy(to + to_offset, from, len);
  52        return len;
  53}
  54
  55/**
  56 * vidtv_memset() - wrapper routine to be used by MPEG-TS
  57 *      generator, in order to avoid going past the
  58 *      output buffer.
  59 * @to: Starting element to set
  60 * @to_offset:  Starting position of the @to buffer to be filled.
  61 * @to_size:    Size of the @to buffer.
  62 * @c:          The value to set the memory to.
  63 * @len:        Number of elements to be copy from @from buffer
  64 *      into @to+ @to_offset buffer.
  65 *
  66 * Note:
  67 *      Real digital TV demod drivers should not have memset
  68 *      wrappers. We use it here because emulating MPEG-TS
  69 *      generation at kernelspace requires some extra care.
  70 *
  71 * Return:
  72 *      Returns the number of bytes written
  73 */
  74u32 vidtv_memset(void *to,
  75                 size_t to_offset,
  76                 size_t to_size,
  77                 const int c,
  78                 size_t len)
  79{
  80        if (unlikely(to_offset + len > to_size)) {
  81                pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
  82                                   to_offset + len,
  83                                   to_size);
  84                return 0;
  85        }
  86
  87        memset(to + to_offset, c, len);
  88        return len;
  89}
  90