结构体 ff_pad_helper_AVBPrint 

#[repr(C)]
pub struct ff_pad_helper_AVBPrint {
    pub str_: *mut c_char,
    pub len: c_uint,
    pub size: c_uint,
    pub size_max: c_uint,
    pub reserved_internal_buffer: [c_char; 1],
}

Buffer to print data progressively

The string buffer grows as necessary and is always 0-terminated. The content of the string is never accessed, and thus is encoding-agnostic and can even hold binary data.

Small buffers are kept in the structure itself, and thus require no memory allocation at all (unless the contents of the buffer is needed after the structure goes out of scope). This is almost as lightweight as declaring a local char buf[512].

The length of the string can go beyond the allocated size: the buffer is then truncated, but the functions still keep account of the actual total length.

In other words, AVBPrint.len can be greater than AVBPrint.size and records the total length of what would have been to the buffer if there had been enough memory.

Append operations do not need to be tested for failure: if a memory allocation fails, data stop being appended to the buffer, but the length is still updated. This situation can be tested with av_bprint_is_complete().

The AVBPrint.size_max field determines several possible behaviours:

• size_max = -1 (= UINT_MAX) or any large value will let the buffer be reallocated as necessary, with an amortized linear cost.
• size_max = 0 prevents writing anything to the buffer: only the total length is computed. The write operations can then possibly be repeated in a buffer with exactly the necessary size (using size_init = size_max = len + 1).
• size_max = 1 is automatically replaced by the exact size available in the structure itself, thus ensuring no dynamic memory allocation. The internal buffer is large enough to hold a reasonable paragraph of text, such as the current paragraph.

Fields

str_: *mut c_char

< string so far

len: c_uint

< length so far

size: c_uint

< allocated memory

size_max: c_uint

< maximum allocated memory

reserved_internal_buffer: [c_char; 1]

trait 实现

impl Clone for ff_pad_helper_AVBPrint

fn clone(&self) -> ff_pad_helper_AVBPrint

Returns a duplicate of the value. 阅读更多

fn clone_from(&mut self, source: &Self)

从 source 执行拷贝赋值。 阅读更多

impl Debug for ff_pad_helper_AVBPrint

fn fmt(&self, f: &mut Formatter<'_>) -> Result

使用给定的格式化器格式化该值。 阅读更多

impl PartialEq for ff_pad_helper_AVBPrint

fn eq(&self, other: &ff_pad_helper_AVBPrint) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

测试 !=。默认实现几乎总是足够的，没有充分理由不应被重写。

impl Copy for ff_pad_helper_AVBPrint

impl Eq for ff_pad_helper_AVBPrint

impl StructuralPartialEq for ff_pad_helper_AVBPrint