90 lines
2.5 KiB
C
90 lines
2.5 KiB
C
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// SPDX-License-Identifier: GPL-2.0
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/*
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* The Virtual DVB test driver serves as a reference DVB driver and helps
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* validate the existing APIs in the media subsystem. It can also aid
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* developers working on userspace applications.
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*
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* Copyright (C) 2020 Daniel W. S. Almeida
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__
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#include <linux/printk.h>
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#include <linux/ratelimit.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include "vidtv_common.h"
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/**
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* vidtv_memcpy() - wrapper routine to be used by MPEG-TS
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* generator, in order to avoid going past the
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* output buffer.
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* @to: Starting element to where a MPEG-TS packet will
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* be copied.
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* @to_offset: Starting position of the @to buffer to be filled.
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* @to_size: Size of the @to buffer.
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* @from: Starting element of the buffer to be copied.
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* @len: Number of elements to be copy from @from buffer
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* into @to+ @to_offset buffer.
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*
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* Note:
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* Real digital TV demod drivers should not have memcpy
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* wrappers. We use it here because emulating MPEG-TS
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* generation at kernelspace requires some extra care.
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*
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* Return:
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* Returns the number of bytes written
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*/
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u32 vidtv_memcpy(void *to,
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size_t to_offset,
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size_t to_size,
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const void *from,
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size_t len)
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{
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if (unlikely(to_offset + len > to_size)) {
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pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
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to_offset + len,
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to_size);
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return 0;
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}
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memcpy(to + to_offset, from, len);
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return len;
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}
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/**
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* vidtv_memset() - wrapper routine to be used by MPEG-TS
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* generator, in order to avoid going past the
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* output buffer.
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* @to: Starting element to set
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* @to_offset: Starting position of the @to buffer to be filled.
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* @to_size: Size of the @to buffer.
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* @c: The value to set the memory to.
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* @len: Number of elements to be copy from @from buffer
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* into @to+ @to_offset buffer.
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*
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* Note:
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* Real digital TV demod drivers should not have memset
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* wrappers. We use it here because emulating MPEG-TS
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* generation at kernelspace requires some extra care.
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*
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* Return:
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* Returns the number of bytes written
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*/
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u32 vidtv_memset(void *to,
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size_t to_offset,
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size_t to_size,
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const int c,
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size_t len)
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{
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if (unlikely(to_offset + len > to_size)) {
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pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %zu, had %zu\n",
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to_offset + len,
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to_size);
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return 0;
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}
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memset(to + to_offset, c, len);
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return len;
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}
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