minix/include/sys/stackframe.h

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#ifndef STACK_FRAME_H
#define STACK_FRAME_H
typedef unsigned reg_t; /* machine register */
typedef reg_t segdesc_t;
/* The stack frame layout is determined by the software, but for efficiency
* it is laid out so the assembly code to use it is as simple as possible.
* 80286 protected mode and all real modes use the same frame, built with
* 16-bit registers. Real mode lacks an automatic stack switch, so little
* is lost by using the 286 frame for it. The 386 frame differs only in
* having 32-bit registers and more segment registers. The same names are
* used for the larger registers to avoid differences in the code.
*/
struct stackframe_s {
u16_t gs; /* last item pushed by save */
u16_t fs; /* ^ */
u16_t es; /* | */
u16_t ds; /* | */
reg_t di; /* di through cx are not accessed in C */
reg_t si; /* order is to match pusha/popa */
reg_t fp; /* bp */
reg_t st; /* hole for another copy of sp */
reg_t bx; /* | */
reg_t dx; /* | */
reg_t cx; /* | */
reg_t retreg; /* ax and above are all pushed by save */
reg_t retadr; /* return address for assembly code save() */
reg_t pc; /* ^ last item pushed by interrupt */
reg_t cs; /* | */
reg_t psw; /* | */
reg_t sp; /* | */
reg_t ss; /* these are pushed by CPU during interrupt */
};
#endif /* #ifndef STACK_FRAME_H */