cosmopolitan/libc/intrin/tpenc.S
Justine Tunney 6f7d0cb1c3
Pay off more technical debt
This makes breaking changes to add underscores to many non-standard
function names provided by the c library. MODE=tiny is now tinier and
we now use smaller locks that are better for tiny apps in this mode.
Some headers have been renamed to be in the same folder as the build
package, so it'll be easier to know which build dependency is needed.
Certain old misguided interfaces have been removed. Intel intrinsics
headers are now listed in libc/isystem (but not in the amalgamation)
to help further improve open source compatibility. Header complexity
has also been reduced. Lastly, more shell scripts are now available.
2022-09-12 23:36:56 -07:00

67 lines
2.7 KiB
ArmAsm

/*-*- mode:unix-assembly; indent-tabs-mode:t; tab-width:8; coding:utf-8 -*-│
vi: set et ft=asm ts=8 tw=8 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
above copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
*/
#include "libc/macros.internal.h"
// Encodes Thompson-Pike varint.
//
// @param edi is int to encode
// @return rax is word-encoded byte buffer
// @note invented on a napkin in a new jersey diner
_tpenc: .leafprologue
.profilable
mov %edi,%edi
xor %eax,%eax
cmp $127,%edi
jbe 3f
bsr %edi,%ecx
mov kTpenc-7*(1+1)(,%rcx,2),%ecx
1: mov %edi,%edx
shr $6,%edi
and $0b00111111,%dl
or $0b10000000,%al
or %dl,%al
shl $8,%rax
dec %cl
jnz 1b
2: or %ch,%al
3: or %rdi,%rax
.leafepilogue
.endfn _tpenc,globl
.rodata
.align 4
.underrun
kTpenc: .rept 4 # MSB10 (0x7FF)
.byte 1,0b11000000 # len,mark
.endr
.rept 5 # MSB15 (0xFFFF)
.byte 2,0b11100000 # len,mark
.endr
.rept 5 # MSB20 (0x1FFFFF)
.byte 3,0b11110000 # len,mark
.endr
.rept 5 # MSB25 (0x3FFFFFF)
.byte 4,0b11111000 # len,mark
.endr
.rept 6 # MSB31 (0xffffffff)
.byte 5,0b11111100 # len,mark
.endr
.zero 2
.endobj kTpenc
.overrun