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 // Common register allocation.
  41 #if CPUFAM_X86
  42 #  define COUNT ecx
  43 #endif
  44 #if CPUFAM_AMD64 && ABI_SYSV
  45 #  define COUNT ecx
  46 #endif
  47 #if CPUFAM_AMD64 && ABI_WIN
  48 #  define COUNT r8d
  49 #endif
  50
  51 FUNC(rand_quick_x86ish_rdrand)
  52         // Enter with a pointer to the random context in the first argument.
  53         // Return zero on success, or -1 on error.
  54
  55 #if CPUFAM_X86
  56         mov     edx, [SP + 4]
  57         stalloc 28
  58 #endif
  59 #if CPUFAM_AMD64 && ABI_SYSV
  60         stalloc 8
  61 #endif
  62 #if CPUFAM_AMD64 && ABI_WIN
  63         stalloc 40
  64 #endif
  65   endprologue
  66
  67         // Try to fetch a random number.
  68         mov     COUNT, 16
  69 0:      rdrand  AX
  70         jc      1f
  71         dec     COUNT
  72         jnz     0b
  73
  74         // Failed.
  75         mov     eax, -1
  76         jmp     9f
  77
  78         // Success.
  79 1:
  80 #if CPUFAM_X86
  81         mov     [SP + 16], AX
  82         lea     ecx, [SP + 16]
  83         mov     dword ptr [SP + 12], 32
  84         mov     dword ptr [SP + 8], 4
  85         mov     [SP + 4], ecx
  86         mov     [SP + 0], edx
  87 #endif
  88 #if CPUFAM_AMD64 && ABI_SYSV
  89         mov     [SP + 0], AX
  90         mov     rsi, SP
  91         mov     edx, 8
  92         mov     ecx, 64
  93 #endif
  94 #if CPUFAM_AMD64 && ABI_WIN
  95         mov     [SP + 32], AX
  96         lea     rdx, [SP + 32]
  97         mov     r8d, 8
  98         mov     r9d, 64
  99 #endif
 100         callext F(rand_add)
 101         xor     eax, eax
 102
 103         // Done.
 104 9:
 105 #if CPUFAM_X86
 106         stfree  28
 107 #endif
 108 #if CPUFAM_AMD64 && ABI_SYSV
 109         stfree  8
 110 #endif
 111 #if CPUFAM_AMD64 && ABI_WIN
 112         stfree  40
 113 #endif
 114         ret
 115 ENDFUNC
 116
 117 #undef COUNT
 118
 119 ///----- That's all, folks --------------------------------------------------