std::math::big: minor optimizations

std/math/big/bits.jule

@@ -316,23 +316,23 @@ fn karatsuba(mut x: bits, mut y: bits): bits {
 		ret basicMul(x, y)
 	}
 	m := max(len(x), len(y)) >> 1
-	mut x1 := cloneBits(rsh(x, m))
+	mut x1 := rsh(x, m)
 	mut x0 := cloneBits(x)
 	subRes(x0, lsh(x1, m))
-	mut y1 := cloneBits(rsh(y, m))
+	mut y1 := rsh(y, m)
 	mut y0 := cloneBits(y)
 	subRes(y0, lsh(y1, m))
 	mut z2 := karatsuba(x1, y1)
 	mut z0 := karatsuba(x0, y0)
-	addRes(x1, x0)
-	addRes(y1, y0)
-	mut z1 := karatsuba(x1, y1)
+	addRes(x0, x1)
+	addRes(y0, y1)
+	mut z1 := karatsuba(x0, y0)
 	subRes(z1, z2)
 	subRes(z1, z0)
-	mut r := lsh(z2, m << 1)
-	addRes(r, lsh(z1, m))
-	addRes(r, z0)
-	ret r
+	z1 = lsh(z1, m)
+	addRes(z1, z0)
+	addRes(z1, lsh(z2, m << 1))
+	ret z1
 }
 
 // Recursion division algorithm. It will update left operand if necessary.

std/math/big/conv.jule

@@ -172,9 +172,10 @@ fn formatDecimalPart(mut &buf: []byte, m: byte) {
 fn formatDecimal(&b: bits): str {
 	mut buf := make([]byte, 1, len(b) >> 1 + 1)
 	buf[0] = '0'
-	for _, bit in formatBinary(b) {
+	mut i := len(b) - 1
+	for i >= 0; i-- {
 		formatDecimalPart(buf, 1)
-		if bit == '1' {
+		if b[i] == 0b1 {
 			formatDecimalPart(buf, 0)
 		}
 	}