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/*
* MEM.H -- Define the dictionary, the stack, indices of various kinds,
* and ways of converting the indices into true address pointers.
*
* Structures that live within the dictionary may use pointers to
* point at other structures (such as the task and parameter chains) but
* things that simply point AT the dictionary and that move around are indices
* into what appears to be the array of unsigned integers called dictionary.
* This is to facilitate putting things of disparate types into the array.
*/
/* bytes per int;
* typically used when putting things in the dictionary like strings, operands
* and codeentries. also, the pc must be advanced in ints.
*
* N.B. it is FUNDAMENTALLY ASSUMED throughout that an int is large enough to
* hold a pointer to an int. Further, although casts are used carefully as
* much as possible and so a good compiler will do much of the work,
* it is also pretty much taken for granted that all pointers are the
* same size, in particular that (char *) is the same size as (unsigned *).
*/
#define BPI (sizeof (memel))
#define btoi(x) ((int)((((x)+BPI-1)/BPI))) /* avoid promotion to unsigned */
#define dtoi(x) ((int)(sizeof(double))/(sizeof(memel))*x)
/* the dictionary starts at the top of the system break and grows as needed.
* if this is hard to do on your os, declare it as a genuine array and
* forever fix the value of maxd by initializing them in their declarations
* in compile.c. see machdep.c.
*/
extern memel *dictionary; /* base of the dictionary; never moves */
/* ----------
* convert a dictionary index into a structure pointer.
* also, dereference a pointer to a dictionary index.
*/
#define reference(sname,index) ((struct sname *) (&dictionary[index]))
/*
#define dereference(ptr) \
(((unsigned)(char *)(ptr) - (unsigned)(char *)(dictionary))/BPI)
*/
#define dereference(ptr) \
(((char *)(ptr) - (char *)(dictionary))/BPI)
/* ----------
* Generic push/pop memory routines. Can be used to push/pop any integer type
* argument regardless of size, so long as it fits in a memel.
*/
#define push(v) pushmem((memel)v)
#define ppush(v) ppushmem((memel)v)
#define pop popmem
/* ----------
* convert a dictionary index into a genuine address; type will be
* the type of dictionary.
*/
#define daddr(x) (&dictionary[x])
/* ----------
* maxd: smallest d. index that is out of range and will give mem fault if
* referenced. commonly referred to as the "system break".
* topd: next d. index available for use, ie, it is the smallest d. index
* not in use.
* pachead: dictionary index of most recently added package.
* parhead: " pfile.
* envhead: " environment.
*/
extern XINT maxd;
extern XINT topd;
extern XINT pachead;
extern XINT parhead;
extern XINT envhead;
/* ----------
* these are indices into the stack defined in stack.c.
* topcs: the smallest index into stack[], ie, the "top" index of the control
* stack since it grows downwards, that has been used.
* topos: the largest index into stack[], ie, the top of the operand stack
* since it grows upwards, that has been used.
* pc: at compile time, this is the stack[] index at which the next codeentry
* may be compiled; at run time, it is the program counter and points
* to the next codeentry to be run (it is bumped before the "execute"
* cycle begins. see run()).
* basos: not used at compile time, but when compilation ends and runtime
* begins, it is set to pc and thus serves as the base of the operand
* stack as everything below it will be compiled code. when compiling
* starts again, this, and pc, are set to zero to forcibly clear the
* operand stack.
*/
extern memel stack[]; /* space for the stacks */
extern XINT topcs; /* top of control stack */
extern XINT topos; /* top of operand stack */
extern XINT basos; /* base of operand stack */
extern XINT pc; /* program counter */
/* ----------
* reference a codeentry in stack at x.
*/
#define coderef(x) ((struct codeentry *)&stack[x])
extern char *memneed(); /* insures enough core, returns start */
extern char *comdstr(); /* compile string at topd, return start */
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