Minor math tweaks + ipow32f/ipow64f (AssemblyScript#428)

Author: MaxGraey

std/assembly/math.ts

@@ -343,8 +343,7 @@ export namespace NativeMath {
  t = reinterpret<f64>((reinterpret<u64>(t) + 0x80000000) & 0xFFFFFFFFC0000000);
  var s = t * t;
  r = x / s;
- var w = t + t;
- r = (r - t) / (w + r);
+ r = (r - t) / (2 * t + r);
  t = t + t * r;
  return t;
  }
@@ -402,10 +401,7 @@ export namespace NativeMath {
  hx &= 0x7FFFFFFF;
  if (hx >= 0x4086232B) {
  if (isNaN(x)) return x;
- if (x > overflow) {
- x *= Ox1p1023;
- return x;
- }
+ if (x > overflow) return x * Ox1p1023;
  if (x < underflow) return 0;
  }
  var hi: f64, lo: f64 = 0;
@@ -819,8 +815,9 @@ export namespace NativeMath {
  if (iy >= 0x43400000) yisint = 2;
  else if (iy >= 0x3FF00000) {
  k = (iy >> 20) - 0x3FF;
- let offset = select<i32>(52, 20, k > 20) - k;
- let Ly = select<i32>(ly, iy, k > 20);
+ let kcond = k > 20;
+ let offset = select<i32>(52, 20, kcond) - k;
+ let Ly = select<i32>(ly, iy, kcond);
  let jj = Ly >> offset;
  if ((jj << offset) == Ly) yisint = 2 - (jj & 1);
  }
@@ -842,19 +839,24 @@ export namespace NativeMath {
  }
  var ax = builtin_abs<f64>(x), z: f64;
  if (lx == 0) {
- if (ix == 0x7FF00000 || ix == 0 || ix == 0x3FF00000) {
+ if (ix == 0 || ix == 0x7FF00000 || ix == 0x3FF00000) {
  z = ax;
  if (hy < 0) z = 1.0 / z;
  if (hx < 0) {
- if (((ix - 0x3FF00000) | yisint) == 0) z = (z - z) / (z - z);
- else if (yisint == 1) z = -z;
+ if (((ix - 0x3FF00000) | yisint) == 0) {
+ let d = z - z;
+ z = d / d;
+ } else if (yisint == 1) z = -z;
  }
  return z;
  }
  }
  var s = 1.0;
  if (hx < 0) {
- if (yisint == 0) return (x - x) / (x - x);
+ if (yisint == 0) {
+ let d = x - x;
+ return d / d;
+ }
  if (yisint == 1) s = -1.0;
  }
  var t1: f64, t2: f64, p_h: f64, p_l: f64, r: f64, t: f64, u: f64, v: f64, w: f64;
@@ -1105,7 +1107,10 @@ export namespace NativeMath {
  var ey = <i64>(uy >> 52 & 0x7FF);
  var sx = ux >> 63;
  var uy1 = uy << 1;
- if (uy1 == 0 || ex == 0x7FF || isNaN<f64>(y)) return (x * y) / (x * y);
+ if (uy1 == 0 || ex == 0x7FF || isNaN<f64>(y)) {
+ let m = x * y;
+ return m / m;
+ }
  var ux1 = ux << 1;
  if (ux1 <= uy1) {
  if (ux1 == uy1) return 0 * x;
@@ -1157,7 +1162,10 @@ export namespace NativeMath {
  var ex = <i64>(ux >> 52 & 0x7FF);
  var ey = <i64>(uy >> 52 & 0x7FF);
  var sx = <i32>(ux >> 63);
- if (uy << 1 == 0 || ex == 0x7FF || isNaN(y)) return (x * y) / (x * y);
+ if (uy << 1 == 0 || ex == 0x7FF || isNaN(y)) {
+ let m = x * y;
+ return m / m;
+ }
  if (ux << 1 == 0) return x;
  var uxi = ux;
  if (!ex) {
@@ -1236,7 +1244,7 @@ function expo2f(x: f32): f32 { // exp(x)/2 for x >= log(DBL_MAX)
  const // see: musl/src/math/__expo2f.c
  k = <u32>235,
  kln2 = reinterpret<f32>(0x4322E3BC); // 0x1.45c778p+7f
- var scale = reinterpret<f32>(<u32>(0x7F + k / 2) << 23);
+ var scale = reinterpret<f32>(<u32>(0x7F + (k >> 1)) << 23);
  return NativeMathf.exp(x - kln2) * scale * scale;
 }
 
@@ -1424,7 +1432,7 @@ export namespace NativeMathf {
  if (iy == 0) {
  switch (m) {
  case 0:
- case 1: return y;
+ case 1: return  y;
  case 2: return pi;
  case 3: return -pi;
  }
@@ -1538,12 +1546,8 @@ export namespace NativeMathf {
  hx &= 0x7FFFFFFF;
  if (hx >= 0x42AEAC50) {
  if (hx >= 0x42B17218) {
- if (!sign_) {
- x *= Ox1p127f;
- return x;
- } else {
- if (hx >= 0x42CFF1B5) return 0;
- }
+ if (!sign_) return x * Ox1p127f;
+ else if (hx >= 0x42CFF1B5) return 0;
  }
  }
  var hi: f32, lo: f32;
@@ -1889,8 +1893,9 @@ export namespace NativeMathf {
  if (iy >= 0x4B800000) yisint = 2;
  else if (iy >= 0x3F800000) {
  k = (iy >> 23) - 0x7F;
- j = iy >> (23 - k);
- if ((j << (23 - k)) == iy) yisint = 2 - (j & 1);
+ let ki = 23 - k;
+ j = iy >> ki;
+ if ((j << ki) == iy) yisint = 2 - (j & 1);
  }
  }
  if (iy == 0x7F800000) { // y is +-inf
@@ -1909,14 +1914,20 @@ export namespace NativeMathf {
  z = ax;
  if (hy < 0) z = 1.0 / z;
  if (hx < 0) {
- if (((ix - 0x3F800000) | yisint) == 0) z = (z - z) / (z - z);
+ if (((ix - 0x3F800000) | yisint) == 0) {
+ let d = z - z;
+ z = d / d;
+ }
  else if (yisint == 1) z = -z;
  }
  return z;
  }
  var sn = <f32>1.0;
  if (hx < 0) {
- if (yisint == 0) return (x - x) / (x - x);
+ if (yisint == 0) {
+ let d = x - x;
+ return d / d;
+ }
  if (yisint == 1) sn = -1.0;
  }
  var t1: f32, t2: f32, r: f32, s: f32, t: f32, u: f32, v: f32, w: f32, p_h: f32, p_l: f32;
@@ -2159,7 +2170,10 @@ export namespace NativeMathf {
  var ey = <i32>(uy >> 23 & 0xFF);
  var sx = ux & 0x80000000;
  var uy1 = uy << 1;
- if (uy1 == 0 || ex == 0xFF || isNaN<f32>(y)) return (x * y) / (x * y);
+ if (uy1 == 0 || ex == 0xFF || isNaN<f32>(y)) {
+ let m = x * y;
+ return m / m;
+ }
  var ux1 = ux << 1;
  if (ux1 <= uy1) {
  if (ux1 == uy1) return 0 * x;
@@ -2380,3 +2394,27 @@ export function ipow64(x: i64, e: i32): i64 {
  }
  return out;
 }
+
+export function ipow32f(x: f32, e: i32): f32 {
+ var sign = e >> 31;
+ e = (e + sign) ^ sign; // abs(e)
+ var out: f32 = 1;
+ while (e) {
+ out *= select<f32>(x, 1.0, e & 1);
+ e >>= 1;
+ x *= x;
+ }
+ return sign ? <f32>1.0 / out : out;
+}
+
+export function ipow64f(x: f64, e: i32): f64 {
+ var sign = e >> 31;
+ e = (e + sign) ^ sign; // abs(e)
+ var out = 1.0;
+ while (e) {
+ out *= select(x, 1.0, e & 1);
+ e >>= 1;
+ x *= x;
+ }
+ return sign ? 1.0 / out : out;
+}