/*-*- 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 │ │ │ │ This program is free software; you can redistribute it and/or modify │ │ it under the terms of the GNU General Public License as published by │ │ the Free Software Foundation; version 2 of the License. │ │ │ │ This program is distributed in the hope that it will be useful, but │ │ WITHOUT ANY WARRANTY; without even the implied warranty of │ │ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU │ │ General Public License for more details. │ │ │ │ You should have received a copy of the GNU General Public License │ │ along with this program; if not, write to the Free Software │ │ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA │ │ 02110-1301 USA │ ╚─────────────────────────────────────────────────────────────────────────────*/ #include "libc/macros.h" .source __FILE__ / 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 kTpenc: .rept 4 # MSB≤10 (0x7FF) .byte 1,0b11000000 # len,mark .endr .rept 5 # MSB≤15 (0xFFFF) .byte 2,0b11100000 # len,mark .endr .rept 5 # MSB≤20 (0x1FFFFF) .byte 3,0b11110000 # len,mark .endr .rept 5 # MSB≤25 (0x3FFFFFF) .byte 4,0b11111000 # len,mark .endr .rept 6 # MSB≤31 (0xffffffff) .byte 5,0b11111100 # len,mark .endr .zero 2 .endobj kTpenc