rand: add full precision f32 and f64 random functions; fix f32/f64 multipliers (#16875)

vlib/math/bits/unsafe_bits.js.v

@@ -0,0 +1,59 @@
+module bits
+
+// f32_bits returns the IEEE 754 binary representation of f,
+// with the sign bit of f and the result in the same bit position.
+// f32_bits(f32_from_bits(x)) == x.
+pub fn f32_bits(f f32) u32 {
+	p := u32(0)
+	#let buffer = new ArrayBuffer(4)
+	#let floatArr = new Float32Array(buffer)
+	#floatArr[0] = f.val
+	#let uintArr = new Uint32Array(buffer)
+	#p.val = uintArr[0]
+
+	return p
+}
+
+// f32_from_bits returns the floating-point number corresponding
+// to the IEEE 754 binary representation b, with the sign bit of b
+// and the result in the same bit position.
+// f32_from_bits(f32_bits(x)) == x.
+pub fn f32_from_bits(b u32) f32 {
+	p := f32(0.0)
+	#let buffer = new ArrayBuffer(4)
+	#let floatArr = new Float32Array(buffer)
+	#let uintArr = new Uint32Array(buffer)
+	#uintArr[0] = Number(b.val)
+	#p.val = floatArr[0]
+
+	return p
+}
+
+// f64_bits returns the IEEE 754 binary representation of f,
+// with the sign bit of f and the result in the same bit position,
+// and f64_bits(f64_from_bits(x)) == x.
+pub fn f64_bits(f f64) u64 {
+	p := u64(0)
+	#let buffer = new ArrayBuffer(8)
+	#let floatArr = new Float64Array(buffer)
+	#floatArr[0] = f.val
+	#let uintArr = new BigUint64Array(buffer)
+	#p.val = uintArr[0]
+
+	return p
+}
+
+// f64_from_bits returns the floating-point number corresponding
+// to the IEEE 754 binary representation b, with the sign bit of b
+// and the result in the same bit position.
+// f64_from_bits(f64_bits(x)) == x.
+pub fn f64_from_bits(b u64) f64 {
+	p := 0.0
+	#let buffer = new ArrayBuffer(8)
+	#let floatArr = new Float64Array(buffer)
+	#let uintArr = new BigUint64Array(buffer)
+	#uintArr[0] = b.val
+	#p.val = floatArr[0]
+
+	return p
+}