diff options
Diffstat (limited to 'drivers/media/test-drivers/vidtv/vidtv_common.c')
-rw-r--r-- | drivers/media/test-drivers/vidtv/vidtv_common.c | 89 |
1 files changed, 89 insertions, 0 deletions
diff --git a/drivers/media/test-drivers/vidtv/vidtv_common.c b/drivers/media/test-drivers/vidtv/vidtv_common.c new file mode 100644 index 000000000000..9093df32e0ab --- /dev/null +++ b/drivers/media/test-drivers/vidtv/vidtv_common.c @@ -0,0 +1,89 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * The Virtual DVB test driver serves as a reference DVB driver and helps + * validate the existing APIs in the media subsystem. It can also aid + * developers working on userspace applications. + * + * Copyright (C) 2020 Daniel W. S. Almeida + */ +#define pr_fmt(fmt) KBUILD_MODNAME ":%s, %d: " fmt, __func__, __LINE__ + +#include <linux/printk.h> +#include <linux/ratelimit.h> +#include <linux/string.h> +#include <linux/types.h> + +#include "vidtv_common.h" + +/** + * vidtv_memcpy() - wrapper routine to be used by MPEG-TS + * generator, in order to avoid going past the + * output buffer. + * @to: Starting element to where a MPEG-TS packet will + * be copied. + * @to_offset: Starting position of the @to buffer to be filled. + * @to_size: Size of the @to buffer. + * @from: Starting element of the buffer to be copied. + * @len: Number of elements to be copy from @from buffer + * into @to+ @to_offset buffer. + * + * Note: + * Real digital TV demod drivers should not have memcpy + * wrappers. We use it here because emulating MPEG-TS + * generation at kernelspace requires some extra care. + * + * Return: + * Returns the number of bytes written + */ +u32 vidtv_memcpy(void *to, + size_t to_offset, + size_t to_size, + const void *from, + size_t len) +{ + if (unlikely(to_offset + len > to_size)) { + pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %lu, had %zu\n", + to_offset + len, + to_size); + return 0; + } + + memcpy(to + to_offset, from, len); + return len; +} + +/** + * vidtv_memset() - wrapper routine to be used by MPEG-TS + * generator, in order to avoid going past the + * output buffer. + * @to: Starting element to set + * @to_offset: Starting position of the @to buffer to be filled. + * @to_size: Size of the @to buffer. + * @c: The value to set the memory to. + * @len: Number of elements to be copy from @from buffer + * into @to+ @to_offset buffer. + * + * Note: + * Real digital TV demod drivers should not have memset + * wrappers. We use it here because emulating MPEG-TS + * generation at kernelspace requires some extra care. + * + * Return: + * Returns the number of bytes written + */ +u32 vidtv_memset(void *to, + size_t to_offset, + size_t to_size, + const int c, + size_t len) +{ + if (unlikely(to_offset + len > to_size)) { + pr_err_ratelimited("overflow detected, skipping. Try increasing the buffer size. Needed %lu, had %zu\n", + to_offset + len, + to_size); + return 0; + } + + memset(to + to_offset, c, len); + return len; +} |