Category : C Source Code
Archive   : XTCPRO.ZIP
Filename : PMOM.H

/* -------------- pmom.h ----------------- */

/*
* Include this header file in the source files for
* the root and overlay modules of an overlay program
*/

#define MAXARGS 10

/* --------- the program and DOS context -------- */
typedef struct {
unsigned ss; /* stack segment */
unsigned sp; /* stack pointer */
unsigned psp; /* program segment prefix */
char far *dta; /* disk transfer address */
} CONTEXT;

extern CONTEXT rctx; /* context of the root module */
extern CONTEXT octx; /* context of the overlay module */

#define ROOTREGS IREGS rtregs
#define ROOTFUNCTION far interrupt

/* ------ enter a root function from an overlay call ------- */
#define ENTER \
{ \
disable(); \
octx.ss=_SS; \
octx.sp=_SP; \
_SS=rctx.ss; \
_SP=rctx.sp; \
_BP=_SP; \
enable(); \
octx.dta=getdta(); \
setdta(rctx.dta); \
_AH = 0x51; \
geninterrupt(0x21); \
octx.psp = _BX; \
_BX = _psp; \
_AH = 0x50; \
geninterrupt(0x21); \
}

/* ------- exit from a root function ------- */
#define EXIT \
{ \
_BX = octx.psp; \
_AH = 0x50; \
geninterrupt(0x21); \
setdta(octx.dta); \
disable(); \
_SS=octx.ss; \
_SP=octx.sp; \
_BP=_SP; \
enable(); \
}

/* ----- return a value from a root function ------- */
#define RETURN(r) \
{ \
rtregs.ax=(unsigned)((r) & 0xffff); \
rtregs.dx=(unsigned)((r) >> 16); \
}

/* -------- overlay function prototypes ---------- */
int load_overlay(char *, ...);
void far *getarg(int);