src/farptr.h

   1 // Code to access multiple segments within gcc.
   2 //
   3 // Copyright (C) 2008  Kevin O'Connor <kevin@koconnor.net>
   4 //
   5 // This file may be distributed under the terms of the GNU GPLv3 license.
   6
   7 #define READ8_SEG(SEG, var) ({                                          \
   8     u8 __value;                                                         \
   9     __asm__ __volatile__("movb %%" #SEG ":%1, %b0"                      \
  10                          : "=Qi"(__value) : "m"(var));                  \
  11     __value; })
  12 #define READ16_SEG(SEG, var) ({                                         \
  13     u16 __value;                                                        \
  14     __asm__ __volatile__("movw %%" #SEG ":%1, %w0"                      \
  15                          : "=ri"(__value) : "m"(var));                  \
  16     __value; })
  17 #define READ32_SEG(SEG, var) ({                                         \
  18     u32 __value;                                                        \
  19     __asm__ __volatile__("movl %%" #SEG ":%1, %0"                       \
  20                          : "=ri"(__value) : "m"(var));                  \
  21     __value; })
  22 #define WRITE8_SEG(SEG, var, value)                     \
  23     __asm__ __volatile__("movb %b0, %%" #SEG ":%1"      \
  24                          : : "Q"(value), "m"(var))
  25 #define WRITE16_SEG(SEG, var, value)                    \
  26     __asm__ __volatile__("movw %w0, %%" #SEG ":%1"      \
  27                          : : "r"(value), "m"(var))
  28 #define WRITE32_SEG(SEG, var, value)                    \
  29     __asm__ __volatile__("movl %0, %%" #SEG ":%1"       \
  30                          : : "r"(value), "m"(var))
  31
  32 #define GET_VAR(seg, var) ({                                    \
  33     typeof(var) __val;                                          \
  34     if (__builtin_types_compatible_p(typeof(__val), u8))        \
  35         __val = READ8_SEG(seg, var);                            \
  36     else if (__builtin_types_compatible_p(typeof(__val), u16))  \
  37         __val = READ16_SEG(seg, var);                           \
  38     else if (__builtin_types_compatible_p(typeof(__val), u32))  \
  39         __val = READ32_SEG(seg, var);                           \
  40     __val; })
  41
  42 #define SET_VAR(seg, var, val) do {                               \
  43         if (__builtin_types_compatible_p(typeof(var), u8))        \
  44             WRITE8_SEG(seg, var, (val));                          \
  45         else if (__builtin_types_compatible_p(typeof(var), u16))  \
  46             WRITE16_SEG(seg, var, (val));                         \
  47         else if (__builtin_types_compatible_p(typeof(var), u32))  \
  48             WRITE32_SEG(seg, var, (val));                         \
  49     } while (0)
  50
  51 #define SET_SEG(SEG, value)                                     \
  52     __asm__ __volatile__("movw %w0, %%" #SEG : : "r"(value))
  53 #define GET_SEG(SEG) ({                                         \
  54     u16 __seg;                                                  \
  55     __asm__ __volatile__("movw %%" #SEG ", %w0" : "=r"(__seg)); \
  56     __seg;})
  57