mdw@git.distorted.org.uk Git - catacomb/blob - rand/rand-x86ish.S

   1 /// -*- mode: asm; asm-comment-char: ?/ -*-
   2 ///
   3 /// Random-number support for x86
   4 ///
   5 /// (c) 2019 Straylight/Edgeware
   6 ///
   7
   8 ///----- Licensing notice ---------------------------------------------------
   9 ///
  10 /// This file is part of Catacomb.
  11 ///
  12 /// Catacomb is free software: you can redistribute it and/or modify it
  13 /// under the terms of the GNU Library General Public License as published
  14 /// by the Free Software Foundation; either version 2 of the License, or
  15 /// (at your option) any later version.
  16 ///
  17 /// Catacomb is distributed in the hope that it will be useful, but
  18 /// WITHOUT ANY WARRANTY; without even the implied warranty of
  19 /// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  20 /// Library General Public License for more details.
  21 ///
  22 /// You should have received a copy of the GNU Library General Public
  23 /// License along with Catacomb.  If not, write to the Free Software
  24 /// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
  25 /// USA.
  26
  27 ///--------------------------------------------------------------------------
  28 /// Preliminaries.
  29
  30 #include "config.h"
  31 #include "asm-common.h"
  32
  33         .extern F(rand_add)
  34
  35         .text
  36
  37 ///--------------------------------------------------------------------------
  38 /// Quick random generation.
  39
  40 FUNC(rand_quick_x86ish_rdrand)
  41         // Enter with a pointer to the random context in the first argument.
  42         // Return zero on success, or -1 on error.
  43
  44 #if CPUFAM_X86
  45         mov     edx, [SP + 4]
  46         stalloc 28
  47 #  define COUNT ecx
  48 #endif
  49 #if CPUFAM_AMD64 && ABI_SYSV
  50         stalloc 8
  51 #  define COUNT ecx
  52 #endif
  53 #if CPUFAM_AMD64 && ABI_WIN
  54         stalloc 40
  55 #  define COUNT r8d
  56 #endif
  57   endprologue
  58
  59         // Try to fetch a random number.
  60         mov     COUNT, 16
  61 0:      rdrand  AX
  62         jc      1f
  63         dec     COUNT
  64         jnz     0b
  65
  66         // Failed.
  67         mov     eax, -1
  68         jmp     9f
  69
  70         // Success.
  71 1:
  72 #if CPUFAM_X86
  73         mov     [SP + 16], AX
  74         lea     ecx, [SP + 16]
  75         mov     dword ptr [SP + 12], 32
  76         mov     dword ptr [SP + 8], 4
  77         mov     [SP + 4], ecx
  78         mov     [SP + 0], edx
  79 #endif
  80 #if CPUFAM_AMD64 && ABI_SYSV
  81         mov     [SP + 0], AX
  82         mov     rsi, SP
  83         mov     edx, 8
  84         mov     ecx, 64
  85 #endif
  86 #if CPUFAM_AMD64 && ABI_WIN
  87         mov     [SP + 32], AX
  88         lea     rdx, [SP + 32]
  89         mov     r8d, 8
  90         mov     r9d, 64
  91 #endif
  92         callext F(rand_add)
  93         xor     eax, eax
  94
  95         // Done.
  96 9:
  97 #if CPUFAM_X86
  98         stfree  28
  99 #endif
 100 #if CPUFAM_AMD64 && ABI_SYSV
 101         stfree  8
 102 #endif
 103 #if CPUFAM_AMD64 && ABI_WIN
 104         stfree  40
 105 #endif
 106         ret
 107
 108 #undef COUNT
 109
 110 ENDFUNC
 111
 112 ///----- That's all, folks --------------------------------------------------