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