Swiftgram/Source/Details/ASHashing.m
appleguy 465abb1ded [License] Simplify the Texture license to be pure Apache 2 (removing ASDK-Licenses). (#1077)
* [License] Simplify the Texture license to be pure Apache 2 (removing ASDK-Licenses)

With permission of the Facebook Open Source team, we are simplifying the Texture
license so that clients can rely on the Apache 2 terms that most of Texture is
already covered by. This means that code originally forked from AsyncDisplayKit
will be re-licensed from "BSD 3-clause + PATENTS v2" to Apache 2 without a
PATENTS file.

After getting confirmation that the updates to these core files look good, we'll
propagate this new license header to all files (in this same PR) and get sign-off
from all parties before landing.

* [License] Update all Texture source files to be pure Apache 2.

* Changelog entry for Apache 2 license update.

* Revert "[License] Update all Texture source files to be pure Apache 2."

This reverts commit ffa0fbbba9717d871dd16c4b07539f2f8208fc2b.

* [License] Update all Texture source files to be pure Apache 2, maintaining copyrights.

* [License] Update CONTRIBUTING, README, Podspec & Dangerfile.
2018-08-28 07:39:18 -07:00

39 lines
1.1 KiB
Objective-C

//
// ASHashing.m
// Texture
//
// Copyright (c) Pinterest, Inc. All rights reserved.
// Licensed under Apache 2.0: http://www.apache.org/licenses/LICENSE-2.0
//
#import <AsyncDisplayKit/ASHashing.h>
#define ELF_STEP(B) T1 = (H << 4) + B; T2 = T1 & 0xF0000000; if (T2) T1 ^= (T2 >> 24); T1 &= (~T2); H = T1;
/**
* The hashing algorithm copied from CoreFoundation CFHashBytes function.
* https://opensource.apple.com/source/CF/CF-1153.18/CFUtilities.c.auto.html
*/
NSUInteger ASHashBytes(void *bytesarg, size_t length) {
/* The ELF hash algorithm, used in the ELF object file format */
uint8_t *bytes = (uint8_t *)bytesarg;
UInt32 H = 0, T1, T2;
SInt32 rem = (SInt32)length;
while (3 < rem) {
ELF_STEP(bytes[length - rem]);
ELF_STEP(bytes[length - rem + 1]);
ELF_STEP(bytes[length - rem + 2]);
ELF_STEP(bytes[length - rem + 3]);
rem -= 4;
}
switch (rem) {
case 3: ELF_STEP(bytes[length - 3]);
case 2: ELF_STEP(bytes[length - 2]);
case 1: ELF_STEP(bytes[length - 1]);
case 0: ;
}
return H;
}
#undef ELF_STEP