Move bit-fields into new package.

src/packages/bit_field.rs

@@ -0,0 +1,198 @@
+#![allow(non_snake_case)]
+
+use crate::plugin::*;
+use crate::{def_package, ExclusiveRange, InclusiveRange, Position, RhaiResultOf, ERR, INT};
+#[cfg(feature = "no_std")]
+use std::prelude::v1::*;
+
+def_package! {
+    /// Package of basic bit-field utilities.
+    crate::BitFieldPackage => |lib| {
+        lib.standard = true;
+
+        combine_with_exported_module!(lib, "bit_field", bit_field_functions);
+    }
+}
+
+#[export_module]
+mod bit_field_functions {
+    const BITS: usize = std::mem::size_of::<INT>() * 8;
+
+    #[rhai_fn(return_raw)]
+    pub fn get_bit(value: INT, index: INT) -> RhaiResultOf<bool> {
+        if index >= 0 {
+            let offset = index as usize;
+
+            if offset >= BITS {
+                Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into())
+            } else {
+                Ok((value & (1 << offset)) != 0)
+            }
+        } else if let Some(abs_index) = index.checked_abs() {
+            let offset = abs_index as usize;
+
+            // Count from end if negative
+            if offset > BITS {
+                Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into())
+            } else {
+                Ok((value & (1 << (BITS - offset))) != 0)
+            }
+        } else {
+            Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into())
+        }
+    }
+    #[rhai_fn(return_raw)]
+    pub fn set_bit(value: &mut INT, index: INT, new_value: bool) -> RhaiResultOf<()> {
+        if index >= 0 {
+            let offset = index as usize;
+
+            if offset >= BITS {
+                Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into())
+            } else {
+                let mask = 1 << offset;
+                if new_value {
+                    *value |= mask;
+                } else {
+                    *value &= !mask;
+                }
+                Ok(())
+            }
+        } else if let Some(abs_index) = index.checked_abs() {
+            let offset = abs_index as usize;
+
+            // Count from end if negative
+            if offset > BITS {
+                Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into())
+            } else {
+                let mask = 1 << offset;
+                if new_value {
+                    *value |= mask;
+                } else {
+                    *value &= !mask;
+                }
+                Ok(())
+            }
+        } else {
+            Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into())
+        }
+    }
+    #[rhai_fn(name = "get_bits", return_raw)]
+    pub fn get_bits_range(value: INT, range: ExclusiveRange) -> RhaiResultOf<INT> {
+        let from = INT::max(range.start, 0);
+        let to = INT::max(range.end, from);
+        get_bits(value, from, to - from)
+    }
+    #[rhai_fn(name = "get_bits", return_raw)]
+    pub fn get_bits_range_inclusive(value: INT, range: InclusiveRange) -> RhaiResultOf<INT> {
+        let from = INT::max(*range.start(), 0);
+        let to = INT::max(*range.end(), from - 1);
+        get_bits(value, from, to - from + 1)
+    }
+    #[rhai_fn(return_raw)]
+    pub fn get_bits(value: INT, index: INT, bits: INT) -> RhaiResultOf<INT> {
+        if bits < 1 {
+            return Ok(0);
+        }
+
+        let offset = if index >= 0 {
+            let offset = index as usize;
+
+            if offset >= BITS {
+                return Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into());
+            }
+
+            offset
+        } else if let Some(abs_index) = index.checked_abs() {
+            let offset = abs_index as usize;
+
+            // Count from end if negative
+            if offset > BITS {
+                return Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into());
+            }
+            BITS - offset
+        } else {
+            return Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into());
+        };
+
+        let bits = if offset + bits as usize > BITS {
+            BITS - offset
+        } else {
+            bits as usize
+        };
+
+        let mut base = 1;
+        let mut mask = 0;
+
+        for _ in 0..bits {
+            mask |= base;
+            base <<= 1;
+        }
+
+        Ok(((value & (mask << index)) >> index) & mask)
+    }
+    #[rhai_fn(name = "set_bits", return_raw)]
+    pub fn set_bits_range(
+        value: &mut INT,
+        range: ExclusiveRange,
+        new_value: INT,
+    ) -> RhaiResultOf<()> {
+        let from = INT::max(range.start, 0);
+        let to = INT::max(range.end, from);
+        set_bits(value, from, to - from, new_value)
+    }
+    #[rhai_fn(name = "set_bits", return_raw)]
+    pub fn set_bits_range_inclusive(
+        value: &mut INT,
+        range: InclusiveRange,
+        new_value: INT,
+    ) -> RhaiResultOf<()> {
+        let from = INT::max(*range.start(), 0);
+        let to = INT::max(*range.end(), from - 1);
+        set_bits(value, from, to - from + 1, new_value)
+    }
+    #[rhai_fn(return_raw)]
+    pub fn set_bits(value: &mut INT, index: INT, bits: INT, new_value: INT) -> RhaiResultOf<()> {
+        if bits < 1 {
+            return Ok(());
+        }
+
+        let offset = if index >= 0 {
+            let offset = index as usize;
+
+            if offset >= BITS {
+                return Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into());
+            }
+
+            offset
+        } else if let Some(abs_index) = index.checked_abs() {
+            let offset = abs_index as usize;
+
+            // Count from end if negative
+            if offset > BITS {
+                return Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into());
+            }
+            BITS - offset
+        } else {
+            return Err(ERR::ErrorBitFieldBounds(BITS, index, Position::NONE).into());
+        };
+
+        let bits = if offset + bits as usize > BITS {
+            BITS - offset
+        } else {
+            bits as usize
+        };
+
+        let mut base = 1;
+        let mut mask = 0;
+
+        for _ in 0..bits {
+            mask |= base;
+            base <<= 1;
+        }
+
+        *value &= !(mask << index);
+        *value |= (new_value & mask) << index;
+
+        Ok(())
+    }
+}