From 12a47df74e9d2e146c40fe0ad1cf803f09d0c01d Mon Sep 17 00:00:00 2001
From: Trevor Spiteri <tspiteri@ieee.org>
Date: Fri, 10 Aug 2018 14:43:10 +0200
Subject: [PATCH] add some more methods

---
 src/lib.rs    | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++
 src/traits.rs | 17 ++++++++++++
 2 files changed, 90 insertions(+)

diff --git a/src/lib.rs b/src/lib.rs
index 90f5104..3046b32 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -470,6 +470,15 @@ macro_rules! fixed {
                 <$Inner>::checked_shr(self.0, rhs).map($Fixed::from_bits)
             }
 
+            if_signed! {
+                $Signedness =>
+                /// Checked absolute value.
+                #[inline]
+                pub fn checked_abs(self) -> Option<$Fixed> {
+                    <$Inner>::checked_abs(self.0).map($Fixed::from_bits)
+                }
+            }
+
             /// Saturating fixed-point addition.
             #[inline]
             pub fn saturating_add(self, rhs: $Fixed) -> $Fixed {
@@ -548,6 +557,15 @@ macro_rules! fixed {
                 $Fixed(<$Inner>::wrapping_shr(self.0, rhs))
             }
 
+            if_signed! {
+                $Signedness =>
+                /// Wrapping absolute value.
+                #[inline]
+                pub fn wrapping_abs(self) -> $Fixed {
+                    $Fixed(<$Inner>::wrapping_abs(self.0))
+                }
+            }
+
             /// Overflowing negation.
             #[inline]
             pub fn overflowing_neg(self) -> ($Fixed, bool) {
@@ -597,6 +615,61 @@ macro_rules! fixed {
                 ($Fixed(ans), o)
             }
 
+            if_signed! {
+                $Signedness =>
+                /// Overflowing absolute value.
+                #[inline]
+                pub fn overflowing_abs(self) -> ($Fixed, bool) {
+                    let (ans, o) = <$Inner>::overflowing_abs(self.0);
+                    ($Fixed(ans), o)
+                }
+            }
+
+            if_unsigned! {
+                $Signedness => pass_method! {
+                    "Returns `true` if the fixed-point number is \
+                     2<sup><i>k</i></sup> for some <i>k</i>.",
+                    $Fixed($Inner) => fn is_power_of_two(self) -> bool
+                }
+            }
+
+            if_unsigned! {
+                $Signedness => pass_method! {
+                    "Returns the smallest power of two ≥ `self`.",
+                    $Fixed($Inner) => fn next_power_of_two(self)
+                }
+            }
+
+            if_unsigned! {
+                $Signedness =>
+                /// Returns the smallest power of two ≥ `self`, or `None`
+                /// if the next power of two is too large to represent.
+                #[inline]
+                pub fn checked_next_power_of_two(self) -> Option<$Fixed> {
+                    <$Inner>::checked_next_power_of_two(self.0).map($Fixed::from_bits)
+                }
+            }
+
+            if_signed! {
+                $Signedness => pass_method! {
+                    "Returns the absolute value of two ≥ `self`.",
+                    $Fixed($Inner) => fn abs(self)
+                }
+            }
+
+            if_signed! {
+                $Signedness =>
+                /// Returns a number representing the sign of `self`.
+                #[inline]
+                pub fn signum(self) -> $Fixed {
+                    match self.0.cmp(&0) {
+                        Ordering::Equal => $Fixed(0),
+                        Ordering::Greater => <$Fixed as FixedNum>::one().expect("overflow"),
+                        Ordering::Less => <$Fixed as FixedNum>::minus_one().expect("overflow"),
+                    }
+                }
+            }
+
             doc_comment! {
                 concat!(
                     "Creates a fixed-point number of type `",
diff --git a/src/traits.rs b/src/traits.rs
index 2af5c59..ef4b797 100644
--- a/src/traits.rs
+++ b/src/traits.rs
@@ -24,6 +24,7 @@ use {
 pub(crate) trait FixedNum: Copy {
     type Part;
     fn one() -> Option<Self>;
+    fn minus_one() -> Option<Self>;
     fn parts(self) -> (bool, Self::Part, Self::Part);
     #[inline(always)]
     fn int_bits() -> u32 {
@@ -110,6 +111,11 @@ macro_rules! fixed_num_unsigned {
                 }
             }
 
+            #[inline]
+            fn minus_one() -> Option<Self> {
+                None
+            }
+
             #[inline]
             fn parts(self) -> (bool, $Part, $Part) {
                 let bits = self.to_bits();
@@ -139,6 +145,17 @@ macro_rules! fixed_num_signed {
                 }
             }
 
+            #[inline]
+            fn minus_one() -> Option<Self> {
+                let int_bits = <$Fixed as FixedNum>::int_bits();
+                let frac_bits = <$Fixed as FixedNum>::frac_bits();
+                if int_bits < 1 {
+                    None
+                } else {
+                    Some($Fixed::from_bits(!0 << frac_bits))
+                }
+            }
+
             #[inline]
             fn parts(self) -> (bool, $Part, $Part) {
                 let bits = self.to_bits().wrapping_abs() as $Part;