asm.h

   1 //
   2 // assembler macros to create x86 segments
   3 //
   4
   5 #define SEG_NULLASM                                             \
   6         .word 0, 0;                                             \
   7         .byte 0, 0, 0, 0
   8
   9 // The 0xC0 means the limit is in 4096-byte units
  10 // and (for executable segments) 32-bit mode.
  11 #define SEG_ASM(type,base,lim)                                  \
  12         .word (((lim) >> 12) & 0xffff), ((base) & 0xffff);      \
  13         .byte (((base) >> 16) & 0xff), (0x90 | (type)),         \
  14                 (0xC0 | (((lim) >> 28) & 0xf)), (((base) >> 24) & 0xff)
  15
  16 #define STA_X     0x8       // Executable segment
  17 #define STA_E     0x4       // Expand down (non-executable segments)
  18 #define STA_C     0x4       // Conforming code segment (executable only)
  19 #define STA_W     0x2       // Writeable (non-executable segments)
  20 #define STA_R     0x2       // Readable (executable segments)
  21 #define STA_A     0x1       // Accessed