Make mod structure less insane

Cargo.toml

@@ -2,9 +2,12 @@
 resolver = "3"
 members = [
     "src",
+    "src/common",
     "src/memory",
     "src/memory/endianness",
     "src/memory/bitstream",
+    "src/memory/bitvacuumer",
+    "src/memory/bitstreamcache",
 ]
 
 [workspace.package]

src/common/Cargo.toml

@@ -0,0 +1,15 @@
+[package]
+name = "rawspeed-common"
+version.workspace = true
+authors.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+documentation.workspace = true
+homepage.workspace = true
+repository.workspace = true
+license.workspace = true
+
+[dependencies]
+
+[lib]
+path = "mod.rs"

src/common/common/mod.rs

@@ -0,0 +1,81 @@
+//------------------------------------------------------------------------------
+
+pub trait Integer {}
+impl Integer for u8 {}
+impl Integer for u16 {}
+impl Integer for u32 {}
+impl Integer for u64 {}
+
+pub trait Bitwidth {
+    const BITWIDTH: usize;
+}
+
+macro_rules! impl_bitwidth {
+    ($($t:ty)+) => {
+        $(
+            impl Bitwidth for $t {
+                const BITWIDTH: usize = <$t>::BITS as usize;
+            }
+        )+
+    };
+}
+
+impl_bitwidth!(u8 u16 u32 u64);
+
+pub trait ConstZero {
+    const ZERO: Self;
+}
+
+impl ConstZero for u8 {
+    const ZERO: Self = 0;
+}
+impl ConstZero for u16 {
+    const ZERO: Self = 0;
+}
+impl ConstZero for u32 {
+    const ZERO: Self = 0;
+}
+impl ConstZero for u64 {
+    const ZERO: Self = 0;
+}
+
+//------------------------------------------------------------------------------
+
+pub fn extract_high_bits<
+    T: Integer + ConstZero + Bitwidth + std::ops::Shr<usize, Output = T>,
+>(
+    value: T,
+    num_bits: usize,
+) -> T {
+    if num_bits == 0 {
+        return <T>::ZERO;
+    }
+    assert!(num_bits <= T::BITWIDTH);
+    let num_low_bits_to_skip = T::BITWIDTH - num_bits;
+    assert!(num_low_bits_to_skip < T::BITWIDTH);
+    value >> num_low_bits_to_skip
+}
+
+pub fn extract_low_bits<
+    T: Integer
+        + ConstZero
+        + Bitwidth
+        + std::ops::Shl<usize, Output = T>
+        + std::ops::Shr<usize, Output = T>,
+>(
+    value: T,
+    num_bits: usize,
+) -> T {
+    if num_bits == 0 {
+        return <T>::ZERO;
+    }
+    assert!(num_bits <= T::BITWIDTH);
+    let num_high_padding_bits = T::BITWIDTH - num_bits;
+    assert!(num_high_padding_bits < T::BITWIDTH);
+    (value << num_high_padding_bits) >> num_high_padding_bits
+}
+
+//------------------------------------------------------------------------------
+
+#[cfg(test)]
+mod test;