include/arch/i386/stackframe.h

   1 #ifndef STACK_FRAME_H
   2 #define STACK_FRAME_H
   3
   4 typedef unsigned reg_t;         /* machine register */
   5 typedef reg_t segdesc_t;
   6
   7 /* The stack frame layout is determined by the software, but for efficiency
   8  * it is laid out so the assembly code to use it is as simple as possible.
   9  * 80286 protected mode and all real modes use the same frame, built with
  10  * 16-bit registers.  Real mode lacks an automatic stack switch, so little
  11  * is lost by using the 286 frame for it.  The 386 frame differs only in
  12  * having 32-bit registers and more segment registers.  The same names are
  13  * used for the larger registers to avoid differences in the code.
  14  */
  15 struct stackframe_s {
  16         u16_t gs;                     /* last item pushed by save */
  17         u16_t fs;                     /*  ^ */
  18         u16_t es;                     /*  | */
  19         u16_t ds;                     /*  | */
  20         reg_t di;                     /* di through cx are not accessed in C */
  21         reg_t si;                     /* order is to match pusha/popa */
  22         reg_t fp;                     /* bp */
  23         reg_t st;                     /* hole for another copy of sp */
  24         reg_t bx;                     /*  | */
  25         reg_t dx;                     /*  | */
  26         reg_t cx;                     /*  | */
  27         reg_t retreg;                 /* ax and above are all pushed by save */
  28         reg_t retadr;                 /* return address for assembly code save() */
  29         reg_t pc;                     /*  ^  last item pushed by interrupt */
  30         reg_t cs;                     /*  | */
  31         reg_t psw;                    /*  | */
  32         reg_t sp;                     /*  | */
  33         reg_t ss;                     /* these are pushed by CPU during interrupt */
  34 };
  35
  36 #endif /* #ifndef STACK_FRAME_H */