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Add integer power functions (#212)

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This commit is contained in:
Max Graey
2018-09-09 05:07:27 +03:00
committed by Daniel Wirtz
parent 658ab23ea6
commit c27b6e8951
4 changed files with 1810 additions and 2 deletions
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108
std/assembly/math.ts
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@ -2303,3 +2303,111 @@ export namespace NativeMathf {
return sx ? -x : x;
}
}
export function ipow32(x: i32, e: i32): i32 {
var out = 1;
if (ASC_SHRINK_LEVEL < 1) {
if (e < 0) return 0;
switch (e) {
case 0: return 1;
case 1: return x;
case 2: return x * x;
}
let log = 32 - clz(e);
if (log <= 5) {
// 32 = 2 ^ 5, so need only five cases.
// But some extra cases needs for properly overflowing
switch (log) {
case 5: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 4: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 3: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 2: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 1: {
if (e & 1) out *= x;
}
}
return out;
}
}
while (e > 0) {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
return out;
}
export function ipow64(x: i64, e: i32): i64 {
var out: i64 = 1;
if (ASC_SHRINK_LEVEL < 1) {
if (e < 0) return 0;
switch (e) {
case 0: return 1;
case 1: return x;
case 2: return x * x;
}
let log = 32 - clz(e);
if (log <= 6) {
// 64 = 2 ^ 6, so need only six cases.
// But some extra cases needs for properly overflowing
switch (log) {
case 6: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 5: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 4: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 3: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 2: {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
case 1: {
if (e & 1) out *= x;
}
}
return out;
}
}
while (e > 0) {
if (e & 1) out *= x;
e >>= 1;
x *= x;
}
return out;
}