Added unsigned type arithmetic and type conversion overflow detection.

LICENSE.md

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2023 John C. Griffin,
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -1,39 +1,35 @@
 [![Build Status](https://travis-ci.org/JohnCGriffin/overflow.png)](https://travis-ci.org/JohnCGriffin/overflow)
 # overflow
-Check for int/int8/int16/int64/int32 integer overflow in Golang arithmetic.
+Check for integer overflow in Golang arithmetic and type conversion.
+
 ### Install
-```
+
+```sh
 go get github.com/johncgriffin/overflow
 ```
-Note that because Go has no template types, the majority of repetitive code is 
-generated by overflow_template.sh.  If you have to change an
-algorithm, change it there and regenerate the Go code via:
-```
+
+In order to be compatible with the old code and keep the code simple and readable, the new code still does not use generics, but uses templates to generate code. So the majority of repetitive code is generated by `overflow_template.sh`. 
+
+If you have to change an algorithm, change it there and regenerate the Go code via: 
+```sh
 go generate
 ```
 ### Synopsis
 
-```
-package main
-
-import "fmt"
-import "math"
+#### Arithmetic overflow detection
+```go
 import "github.com/JohnCGriffin/overflow"
 
 func main() {
-
-	addend := math.MaxInt64 - 5
-
-	for i := 0; i < 10; i++ {
-		sum, ok := overflow.Add(addend, i)
-		fmt.Printf("%v+%v -> (%v,%v)\n",
-			addend, i, sum, ok)
-	}
-
+    addend := math.MaxInt64 - 5
+    for i := 0; i < 10; i++ {
+        sum, ok := overflow.Add(addend, i)
+        fmt.Printf("%v+%v -> (%v,%v)\n", addend, i, sum, ok)
+    }
 }
 ```
 yields the output
-```
+```go
 9223372036854775802+0 -> (9223372036854775802,true)
 9223372036854775802+1 -> (9223372036854775803,true)
 9223372036854775802+2 -> (9223372036854775804,true)
@@ -45,40 +41,83 @@ yields the output
 9223372036854775802+8 -> (0,false)
 9223372036854775802+9 -> (0,false)
 ```
+For (u)int types, provide (U)Add, (U)Sub, (U)Mul, (U)Div, (U)Quotient, etc.
 
-For int, int64, and int32 types, provide Add, Add32, Add64, Sub, Sub32, Sub64, etc.  
-Unsigned types not covered at the moment, but such additions are welcome.
+#### Type conversion overflow detection
+```go
+func main() {
+    var i uint
+    for i = math.MaxInt - 5; i <= math.MaxInt+5; i++ {
+        ret, ok := overflow.UintToInt(i)
+        fmt.Printf("%v -> (%v,%v)\n", i, ret, ok)
+    }
+}
+```
+yields the output
+```go
+9223372036854775802 -> (9223372036854775802,true)
+9223372036854775803 -> (9223372036854775803,true)
+9223372036854775804 -> (9223372036854775804,true)
+9223372036854775805 -> (9223372036854775805,true)
+9223372036854775806 -> (9223372036854775806,true)
+9223372036854775807 -> (9223372036854775807,true)
+9223372036854775808 -> (-9223372036854775808,false)
+9223372036854775809 -> (-9223372036854775807,false)
+9223372036854775810 -> (-9223372036854775806,false)
+9223372036854775811 -> (-9223372036854775805,false)
+9223372036854775812 -> (-9223372036854775804,false)
+```
+Provide UintToInt, IntToUint, Uint64ToInt32, Int32ToUint64, etc.
 
-### Stay calm and panic
+#### Get absolute value
+```go
+func main() {
+    normalAbs := func(x int64) int64 {
+        if x < 0 {
+            x = -x
+        }
+        return x
+    }
+    var i1, j1, k1 int64 = -9007199254740993, -9007199254740993, -9007199254740993
+    fmt.Println(int64(math.Abs(float64(i1))))
+    fmt.Println(normalAbs(j1))
+    fmt.Println(overflow.Abs64(k1))
+
+    var i2, j2, k2 int64 = math.MinInt64, math.MinInt64, math.MinInt64
+    fmt.Println(int64(math.Abs(float64(i2))))
+    fmt.Println(normalAbs(j2))
+    fmt.Println(overflow.Abs64(k2))
+}
+```
+yields the output
+```go
+9007199254740992 // Mantissa overflow, precision lost
+9007199254740993
+9007199254740993 true
+-9223372036854775808
+-9223372036854775808
+-9223372036854775808 false // Overflow detected
+```
+
+For int, provides an absolute value including overflow detection.
 
-There's a good case to be made that a panic is an unidiomatic but proper response.  Iff you
-believe that there's no valid way to continue your program after math goes wayward, you can
-use the easier Addp, Mulp, Subp, and Divp versions which return the normal result or panic.
+### Stay calm and panic
 
+There's a good case to be made that a panic is an unidiomatic but proper response. If you believe that there's no valid way to continue your program after math goes wayward, you can use the easier Addp, Mulp, Subp, Divp, IntToUintp, Absp etc, which return the normal result or panic.
 
-- - -
-MIT License
+### Performance considerations
 
-Copyright (c) 2017 John C. Griffin, 
+Compared to integer safe libraries in other languages (e.g. C++), this library uses some seemingly slow operations, such as division. But that doesn't mean these methods will be slow. In fact, because of Go's automatic inlining strategy for short functions and compiler optimizations, these operations are actually very fast in benchmark tests, lightning fast. 
 
-Permission is hereby granted, free of charge, to any person obtaining a copy
-of this software and associated documentation files (the "Software"), to deal
-in the Software without restriction, including without limitation the rights
-to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-copies of the Software, and to permit persons to whom the Software is
-furnished to do so, subject to the following conditions:
+In addition, Go defines the overflow behavior of signed integers, making the detection of signed integer overflow simple and efficient.
 
-The above copyright notice and this permission notice shall be included in all
-copies or substantial portions of the Software.
+Note that using `//go:noinline` in your business function will not affect the inlining of the library function. Only disabling global inlining through `-gcflags="-l"` will affect the inlining of this library function.
 
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
-OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
-SOFTWARE.
+### Basis and dependencies
 
+The library is developed based on Go's official compiler implementation (gc) and language specifications.
 
+### License
 
+[MIT LICENSE](./LICENSE.md)