closedcaption: Convert bitfields to uint8_t for portability reasons

Contrary to what one might believe, this actually reduces the size of
the structs due to alignment constraints. On Linux x86-64 clang/gcc it
reduces the size of the caption_frame_t struct from 7760 bytes to 6800
bytes, on Windows x86-64 MSVC from 11600 bytes to 6800 bytes.

It also causes simpler and potentially faster assembly to be generated
as the values can be directly accessed as uint8_t instead of having to
extract the corresponding bits with bitwise operations.

It also gives us the same ABI with clang/gcc and MSVC.

video/closedcaption/src/c/caption.h

@@ -56,8 +56,8 @@ static inline libcaption_stauts_t libcaption_status_update(libcaption_stauts_t o
 #define SCREEN_COLS 32
 
 typedef struct {
-    unsigned int uln : 1; //< underline
+    uint8_t uln; //< underline
-    unsigned int sty : 3; //< style
+    uint8_t sty; //< style
     utf8_char_t data[5]; //< 4 byte utf8 values plus null term
 } caption_frame_cell_t;
 
@@ -66,9 +66,9 @@ typedef struct {
 } caption_frame_buffer_t;
 
 typedef struct {
-    unsigned int uln : 1; //< underline
+    uint8_t uln; //< underline
-    unsigned int sty : 3; //< style
+    uint8_t sty; //< style
-    unsigned int rup : 2; //< roll-up line count minus 1
+    uint8_t rup; //< roll-up line count minus 1
     int8_t row, col;
     uint16_t cc_data;
 } caption_frame_state_t;

video/closedcaption/src/cea608tott_ffi.rs

@@ -1,86 +1,5 @@
 /* automatically generated by rust-bindgen */
 
-#[repr(C)]
-#[derive(Copy, Clone, Debug, Default, Eq, Hash, Ord, PartialEq, PartialOrd)]
-pub struct __BindgenBitfieldUnit<Storage, Align> {
-    storage: Storage,
-    align: [Align; 0],
-}
-impl<Storage, Align> __BindgenBitfieldUnit<Storage, Align> {
-    #[inline]
-    pub const fn new(storage: Storage) -> Self {
-        Self { storage, align: [] }
-    }
-}
-impl<Storage, Align> __BindgenBitfieldUnit<Storage, Align>
-where
-    Storage: AsRef<[u8]> + AsMut<[u8]>,
-{
-    #[inline]
-    pub fn get_bit(&self, index: usize) -> bool {
-        debug_assert!(index / 8 < self.storage.as_ref().len());
-        let byte_index = index / 8;
-        let byte = self.storage.as_ref()[byte_index];
-        let bit_index = if cfg!(target_endian = "big") {
-            7 - (index % 8)
-        } else {
-            index % 8
-        };
-        let mask = 1 << bit_index;
-        byte & mask == mask
-    }
-    #[inline]
-    pub fn set_bit(&mut self, index: usize, val: bool) {
-        debug_assert!(index / 8 < self.storage.as_ref().len());
-        let byte_index = index / 8;
-        let byte = &mut self.storage.as_mut()[byte_index];
-        let bit_index = if cfg!(target_endian = "big") {
-            7 - (index % 8)
-        } else {
-            index % 8
-        };
-        let mask = 1 << bit_index;
-        if val {
-            *byte |= mask;
-        } else {
-            *byte &= !mask;
-        }
-    }
-    #[inline]
-    pub fn get(&self, bit_offset: usize, bit_width: u8) -> u64 {
-        debug_assert!(bit_width <= 64);
-        debug_assert!(bit_offset / 8 < self.storage.as_ref().len());
-        debug_assert!((bit_offset + (bit_width as usize)) / 8 <= self.storage.as_ref().len());
-        let mut val = 0;
-        for i in 0..(bit_width as usize) {
-            if self.get_bit(i + bit_offset) {
-                let index = if cfg!(target_endian = "big") {
-                    bit_width as usize - 1 - i
-                } else {
-                    i
-                };
-                val |= 1 << index;
-            }
-        }
-        val
-    }
-    #[inline]
-    pub fn set(&mut self, bit_offset: usize, bit_width: u8, val: u64) {
-        debug_assert!(bit_width <= 64);
-        debug_assert!(bit_offset / 8 < self.storage.as_ref().len());
-        debug_assert!((bit_offset + (bit_width as usize)) / 8 <= self.storage.as_ref().len());
-        for i in 0..(bit_width as usize) {
-            let mask = 1 << i;
-            let val_bit_is_set = val & mask == mask;
-            let index = if cfg!(target_endian = "big") {
-                bit_width as usize - 1 - i
-            } else {
-                i
-            };
-            self.set_bit(index + bit_offset, val_bit_is_set);
-        }
-    }
-}
 pub const EIA608_CHAR_COUNT: u32 = 176;
 pub const EIA608_CHAR_NULL: &'static [u8; 1usize] = b"\0";
 pub const EIA608_CHAR_SPACE: &'static [u8; 2usize] = b" \0";
@@ -815,124 +734,27 @@ pub const libcaption_stauts_t_LIBCAPTION_READY: libcaption_stauts_t = 2;
 pub const libcaption_stauts_t_LIBCAPTION_CLEAR: libcaption_stauts_t = 3;
 pub type libcaption_stauts_t = u32;
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Debug, Copy, Clone)]
 pub struct caption_frame_cell_t {
-    pub _bitfield_1: __BindgenBitfieldUnit<[u8; 1usize], u8>,
+    pub uln: u8,
+    pub sty: u8,
     pub data: [utf8_char_t; 5usize],
 }
-impl caption_frame_cell_t {
-    #[inline]
-    pub fn uln(&self) -> ::std::os::raw::c_uint {
-        unsafe { ::std::mem::transmute(self._bitfield_1.get(0usize, 1u8) as u32) }
-    }
-    #[inline]
-    pub fn set_uln(&mut self, val: ::std::os::raw::c_uint) {
-        unsafe {
-            let val: u32 = ::std::mem::transmute(val);
-            self._bitfield_1.set(0usize, 1u8, val as u64)
-        }
-    }
-    #[inline]
-    pub fn sty(&self) -> ::std::os::raw::c_uint {
-        unsafe { ::std::mem::transmute(self._bitfield_1.get(1usize, 3u8) as u32) }
-    }
-    #[inline]
-    pub fn set_sty(&mut self, val: ::std::os::raw::c_uint) {
-        unsafe {
-            let val: u32 = ::std::mem::transmute(val);
-            self._bitfield_1.set(1usize, 3u8, val as u64)
-        }
-    }
-    #[inline]
-    pub fn new_bitfield_1(
-        uln: ::std::os::raw::c_uint,
-        sty: ::std::os::raw::c_uint,
-    ) -> __BindgenBitfieldUnit<[u8; 1usize], u8> {
-        let mut __bindgen_bitfield_unit: __BindgenBitfieldUnit<[u8; 1usize], u8> =
-            Default::default();
-        __bindgen_bitfield_unit.set(0usize, 1u8, {
-            let uln: u32 = unsafe { ::std::mem::transmute(uln) };
-            uln as u64
-        });
-        __bindgen_bitfield_unit.set(1usize, 3u8, {
-            let sty: u32 = unsafe { ::std::mem::transmute(sty) };
-            sty as u64
-        });
-        __bindgen_bitfield_unit
-    }
-}
 #[repr(C)]
 #[derive(Debug, Copy, Clone)]
 pub struct caption_frame_buffer_t {
     pub cell: [[caption_frame_cell_t; 32usize]; 15usize],
 }
 #[repr(C)]
-#[repr(align(4))]
 #[derive(Debug, Copy, Clone)]
 pub struct caption_frame_state_t {
-    pub _bitfield_1: __BindgenBitfieldUnit<[u8; 1usize], u8>,
+    pub uln: u8,
+    pub sty: u8,
+    pub rup: u8,
     pub row: i8,
     pub col: i8,
     pub cc_data: u16,
 }
-impl caption_frame_state_t {
-    #[inline]
-    pub fn uln(&self) -> ::std::os::raw::c_uint {
-        unsafe { ::std::mem::transmute(self._bitfield_1.get(0usize, 1u8) as u32) }
-    }
-    #[inline]
-    pub fn set_uln(&mut self, val: ::std::os::raw::c_uint) {
-        unsafe {
-            let val: u32 = ::std::mem::transmute(val);
-            self._bitfield_1.set(0usize, 1u8, val as u64)
-        }
-    }
-    #[inline]
-    pub fn sty(&self) -> ::std::os::raw::c_uint {
-        unsafe { ::std::mem::transmute(self._bitfield_1.get(1usize, 3u8) as u32) }
-    }
-    #[inline]
-    pub fn set_sty(&mut self, val: ::std::os::raw::c_uint) {
-        unsafe {
-            let val: u32 = ::std::mem::transmute(val);
-            self._bitfield_1.set(1usize, 3u8, val as u64)
-        }
-    }
-    #[inline]
-    pub fn rup(&self) -> ::std::os::raw::c_uint {
-        unsafe { ::std::mem::transmute(self._bitfield_1.get(4usize, 2u8) as u32) }
-    }
-    #[inline]
-    pub fn set_rup(&mut self, val: ::std::os::raw::c_uint) {
-        unsafe {
-            let val: u32 = ::std::mem::transmute(val);
-            self._bitfield_1.set(4usize, 2u8, val as u64)
-        }
-    }
-    #[inline]
-    pub fn new_bitfield_1(
-        uln: ::std::os::raw::c_uint,
-        sty: ::std::os::raw::c_uint,
-        rup: ::std::os::raw::c_uint,
-    ) -> __BindgenBitfieldUnit<[u8; 1usize], u8> {
-        let mut __bindgen_bitfield_unit: __BindgenBitfieldUnit<[u8; 1usize], u8> =
-            Default::default();
-        __bindgen_bitfield_unit.set(0usize, 1u8, {
-            let uln: u32 = unsafe { ::std::mem::transmute(uln) };
-            uln as u64
-        });
-        __bindgen_bitfield_unit.set(1usize, 3u8, {
-            let sty: u32 = unsafe { ::std::mem::transmute(sty) };
-            sty as u64
-        });
-        __bindgen_bitfield_unit.set(4usize, 2u8, {
-            let rup: u32 = unsafe { ::std::mem::transmute(rup) };
-            rup as u64
-        });
-        __bindgen_bitfield_unit
-    }
-}
 #[repr(C)]
 #[derive(Debug, Copy, Clone)]
 pub struct caption_frame_t {