overflow_template.sh

#!/bin/sh

exec > overflow_impl.go

echo "package overflow

// Code generated by overflow_template.sh from 'go generate'. DO NOT EDIT."

for SIZE in 8 16 32 64
do
	echo "
// Add${SIZE} performs + operation on two int${SIZE} operands, returning a result and status.
func Add${SIZE}(a, b int${SIZE}) (int${SIZE}, bool) {
	c := a + b
	if (c > a) == (b > 0) {
		return c, true
	}
	return c, false
}

// Add${SIZE}p is the unchecked panicing version of Add${SIZE}.
func Add${SIZE}p(a, b int${SIZE}) int${SIZE} {
	r, ok := Add${SIZE}(a, b)
	if !ok {
		panic(\"addition overflow\")
	}
	return r
}

// Sub${SIZE} performs - operation on two int${SIZE} operands, returning a result and status.
func Sub${SIZE}(a, b int${SIZE}) (int${SIZE}, bool) {
	c := a - b
	if (c < a) == (b > 0) {
		return c, true
	}
	return c, false
}

// Sub${SIZE}p is the unchecked panicing version of Sub${SIZE}.
func Sub${SIZE}p(a, b int${SIZE}) int${SIZE} {
	r, ok := Sub${SIZE}(a, b)
	if !ok {
		panic(\"subtraction overflow\")
	}
	return r
}

// Mul${SIZE} performs * operation on two int${SIZE} operands returning a result and status.
func Mul${SIZE}(a, b int${SIZE}) (int${SIZE}, bool) {
	if a == 0 || b == 0 {
		return 0, true
	}
	c := a * b
	if (c < 0) == ((a < 0) != (b < 0)) {
		if c/b == a {
			return c, true
		}
	}
	return c, false
}

// Mul${SIZE}p is the unchecked panicing version of Mul${SIZE}.
func Mul${SIZE}p(a, b int${SIZE}) int${SIZE} {
	r, ok := Mul${SIZE}(a, b)
	if !ok {
		panic(\"multiplication overflow\")
	}
	return r
}

// Div${SIZE} performs / operation on two int${SIZE} operands, returning a result and status.
func Div${SIZE}(a, b int${SIZE}) (int${SIZE}, bool) {
	q, _, ok := Quotient${SIZE}(a, b)
	return q, ok
}

// Div${SIZE}p is the unchecked panicing version of Div${SIZE}.
func Div${SIZE}p(a, b int${SIZE}) int${SIZE} {
	r, ok := Div${SIZE}(a, b)
	if !ok {
		panic(\"division failure\")
	}
	return r
}

// Quotient${SIZE} performs / operation on two int${SIZE} operands, returning a quotient,
// a remainder and status.
func Quotient${SIZE}(a, b int${SIZE}) (int${SIZE}, int${SIZE}, bool) {
	if b == 0 {
		return 0, 0, false
	}
	c := a / b
	status := (c < 0) == ((a < 0) != (b < 0)) || (c == 0) // no sign check for 0 quotient
	return c, a%b, status
}
"
done