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Optimize some std mem methods by replacing expensive rem operations to fast bit logic (#24)

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This commit is contained in:
Max Graey
2018-02-12 19:47:32 +02:00
committed by Daniel Wirtz
parent 74f8189ac1
commit 2175e6fbdc
8 changed files with 193 additions and 172 deletions
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20
std/assembly/memory.ts
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@ -5,13 +5,13 @@ function copy_memory(dest: usize, src: usize, n: usize): void {
var w: u32, x: u32;
// copy 1 byte each until src is aligned to 4 bytes
while (n && src % 4) {
while (n && (src & 3)) {
store<u8>(dest++, load<u8>(src++));
n--;
}
// if dst is aligned to 4 bytes as well, copy 4 bytes each
if (dest % 4 == 0) {
if ((dest & 3) == 0) {
while (n >= 16) {
store<u32>(dest , load<u32>(src ));
store<u32>(dest + 4, load<u32>(src + 4));
@ -41,7 +41,7 @@ function copy_memory(dest: usize, src: usize, n: usize): void {
// if dst is not aligned to 4 bytes, use alternating shifts to copy 4 bytes each
// doing shifts if faster when copying enough bytes (here: 32 or more)
if (n >= 32) {
switch (dest % 4) {
switch (dest & 3) {
// known to be != 0
case 1:
w = load<u32>(src);
@ -152,8 +152,8 @@ export function move_memory(dest: usize, src: usize, n: usize): void {
return;
}
if (dest < src) {
if (src % 8 == dest % 8) {
while (dest % 8) {
if ((src & 7) == (dest & 7)) {
while (dest & 7) {
if (!n)
return;
--n;
@ -161,9 +161,9 @@ export function move_memory(dest: usize, src: usize, n: usize): void {
}
while (n >= 8) {
store<u64>(dest, load<u64>(src));
n -= 8;
n -= 8;
dest += 8;
src += 8;
src += 8;
}
}
while (n) {
@ -171,8 +171,8 @@ export function move_memory(dest: usize, src: usize, n: usize): void {
--n;
}
} else {
if (src % 8 == dest % 8) {
while ((dest + n) % 8) {
if ((src & 7) == (dest & 7)) {
while ((dest + n) & 7) {
if (!n)
return;
store<u8>(dest + --n, load<u8>(src + n));
@ -217,7 +217,7 @@ export function set_memory(dest: usize, c: u8, n: usize): void {
n -= k;
n &= -4;
var c32: u32 = -1 / 255 * c;
var c32: u32 = (-1 / 255) * c;
// fill head/tail up to 28 bytes each in preparation
store<u32>(dest, c32);