1 // Copyright (C) 2024 Intel Corporation. 2 // Author(s): Zhao Liu <zhao1.liu@intel.com> 3 // SPDX-License-Identifier: GPL-2.0-or-later 4 5 //! This module provides bit operation extensions to integer types. 6 //! It is usually included via the `qemu_api` prelude. 7 8 use std::ops::{ 9 Add, AddAssign, BitAnd, BitAndAssign, BitOr, BitOrAssign, BitXor, BitXorAssign, Div, DivAssign, 10 Mul, MulAssign, Not, Rem, RemAssign, Shl, ShlAssign, Shr, ShrAssign, 11 }; 12 13 /// Trait for extensions to integer types 14 pub trait IntegerExt: 15 Add<Self, Output = Self> + AddAssign<Self> + 16 BitAnd<Self, Output = Self> + BitAndAssign<Self> + 17 BitOr<Self, Output = Self> + BitOrAssign<Self> + 18 BitXor<Self, Output = Self> + BitXorAssign<Self> + 19 Copy + 20 Div<Self, Output = Self> + DivAssign<Self> + 21 Eq + 22 Mul<Self, Output = Self> + MulAssign<Self> + 23 Not<Output = Self> + Ord + PartialOrd + 24 Rem<Self, Output = Self> + RemAssign<Self> + 25 Shl<Self, Output = Self> + ShlAssign<Self> + 26 Shl<u32, Output = Self> + ShlAssign<u32> + // add more as needed 27 Shr<Self, Output = Self> + ShrAssign<Self> + 28 Shr<u32, Output = Self> + ShrAssign<u32> // add more as needed 29 { 30 const BITS: u32; 31 const MAX: Self; 32 const MIN: Self; 33 const ONE: Self; 34 const ZERO: Self; 35 36 #[inline] 37 #[must_use] bit(start: u32) -> Self38 fn bit(start: u32) -> Self 39 { 40 debug_assert!(start < Self::BITS); 41 42 Self::ONE << start 43 } 44 45 #[inline] 46 #[must_use] mask(start: u32, length: u32) -> Self47 fn mask(start: u32, length: u32) -> Self 48 { 49 /* FIXME: Implement a more elegant check with error handling support? */ 50 debug_assert!(start < Self::BITS && length > 0 && length <= Self::BITS - start); 51 52 (Self::MAX >> (Self::BITS - length)) << start 53 } 54 55 #[inline] 56 #[must_use] deposit<U: IntegerExt>(self, start: u32, length: u32, fieldval: U) -> Self where Self: From<U>57 fn deposit<U: IntegerExt>(self, start: u32, length: u32, 58 fieldval: U) -> Self 59 where Self: From<U> 60 { 61 debug_assert!(length <= U::BITS); 62 63 let mask = Self::mask(start, length); 64 (self & !mask) | ((Self::from(fieldval) << start) & mask) 65 } 66 67 #[inline] 68 #[must_use] extract(self, start: u32, length: u32) -> Self69 fn extract(self, start: u32, length: u32) -> Self 70 { 71 let mask = Self::mask(start, length); 72 (self & mask) >> start 73 } 74 } 75 76 macro_rules! impl_num_ext { 77 ($type:ty) => { 78 impl IntegerExt for $type { 79 const BITS: u32 = <$type>::BITS; 80 const MAX: Self = <$type>::MAX; 81 const MIN: Self = <$type>::MIN; 82 const ONE: Self = 1; 83 const ZERO: Self = 0; 84 } 85 }; 86 } 87 88 impl_num_ext!(u8); 89 impl_num_ext!(u16); 90 impl_num_ext!(u32); 91 impl_num_ext!(u64); 92 93 #[cfg(test)] 94 mod tests { 95 use super::*; 96 97 #[test] test_deposit()98 fn test_deposit() { 99 assert_eq!(15u32.deposit(8, 8, 1u32), 256 + 15); 100 assert_eq!(15u32.deposit(8, 1, 255u8), 256 + 15); 101 } 102 103 #[test] test_extract()104 fn test_extract() { 105 assert_eq!(15u32.extract(2, 4), 3); 106 } 107 108 #[test] test_bit()109 fn test_bit() { 110 assert_eq!(u8::bit(7), 128); 111 assert_eq!(u32::bit(16), 0x10000); 112 } 113 114 #[test] test_mask()115 fn test_mask() { 116 assert_eq!(u8::mask(7, 1), 128); 117 assert_eq!(u32::mask(8, 8), 0xff00); 118 } 119 } 120