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         push    ebx
  58         stalloc 24
  59 #endif
  60 #if CPUFAM_AMD64 && ABI_SYSV
  61         stalloc 8
  62 #endif
  63 #if CPUFAM_AMD64 && ABI_WIN
  64         stalloc 40
  65 #endif
  66   endprologue
  67
  68         // Try to fetch a random number.
  69         mov     COUNT, 16
  70 0:      rdrand  AX
  71         jc      1f
  72         dec     COUNT
  73         jnz     0b
  74
  75         // Failed.
  76         mov     eax, -1
  77         jmp     9f
  78 ENDFUNC
  79
  80 FUNC(rand_quick_x86ish_rdseed)
  81         // Enter with a pointer to the random context in the first argument.
  82         // Return zero on success, or -1 on error.
  83
  84 #if CPUFAM_X86
  85         mov     edx, [SP + 4]
  86         push    ebx
  87         stalloc 24
  88 #endif
  89 #if CPUFAM_AMD64 && ABI_SYSV
  90         stalloc 8
  91 #endif
  92 #if CPUFAM_AMD64 && ABI_WIN
  93         stalloc 40
  94 #endif
  95   endprologue
  96
  97         // Try to fetch a random number.
  98         mov     COUNT, 16
  99 0:      rdseed  AX
 100         jc      1f
 101         dec     COUNT
 102         jnz     0b
 103
 104         // Failed.
 105         mov     eax, -1
 106         jmp     9f
 107
 108         // Success.
 109 1:
 110 #if CPUFAM_X86
 111         ldgot   ebx
 112         mov     [SP + 16], AX
 113         lea     ecx, [SP + 16]
 114         mov     dword ptr [SP + 12], 32
 115         mov     dword ptr [SP + 8], 4
 116         mov     [SP + 4], ecx
 117         mov     [SP + 0], edx
 118 #endif
 119 #if CPUFAM_AMD64 && ABI_SYSV
 120         mov     [SP + 0], AX
 121         mov     rsi, SP
 122         mov     edx, 8
 123         mov     ecx, 64
 124 #endif
 125 #if CPUFAM_AMD64 && ABI_WIN
 126         mov     [SP + 32], AX
 127         lea     rdx, [SP + 32]
 128         mov     r8d, 8
 129         mov     r9d, 64
 130 #endif
 131         callext F(rand_add)
 132         xor     eax, eax
 133
 134         // Done.
 135 9:
 136 #if CPUFAM_X86
 137         stfree  24
 138         pop     ebx
 139 #endif
 140 #if CPUFAM_AMD64 && ABI_SYSV
 141         stfree  8
 142 #endif
 143 #if CPUFAM_AMD64 && ABI_WIN
 144         stfree  40
 145 #endif
 146         ret
 147 ENDFUNC
 148
 149 #undef COUNT
 150
 151 ///----- That's all, folks --------------------------------------------------