src/c/arch.h

   1 /* Architecture */
   2
   3 #ifndef __ARCH_H
   4 #define __ARCH_H
   5
   6 void initArchitecture(int stackSize, int regsCount);
   7
   8 /* Stack */
   9 extern int* stack;
  10 extern int sp;
  11 extern int fp;
  12
  13 void push(int x);
  14 int pop();
  15
  16 /* The stack **WHILE IN A USER PROCEDURE**:
  17         fp -> |      |
  18               | fp   |  - the old fp (before this application)
  19               | ret  |  - return address
  20               | env  |  - points to the enviroment vector
  21               | n    |  - number of arguments
  22               | A0   |  - argument 0
  23               | A1   |  - argument 1
  24               | ...  |  - ...
  25  ST_FRMEND -> | An-1 |  - argument n-1
  26
  27    Note: ST_FRMEND points to the end of the current actvation frame (in fact,
  28          to the last element: An-1). Note that ST_FRMEND does not have to be
  29          equal to [the old fp + 1] (in case we are in the middle of an
  30          application and already pushed some arguments onto the stack).
  31
  32    Note: sp does NOT have to be equal to fp - for example if we are in the
  33          middle of applying a procedure and already pushed some arguments
  34          on to the stack (then sp has changed, but fp has not).
  35
  36    Macros for user procedures:
  37 */
  38 #define ST_ARG(n) (stack[fp-5-(n)])
  39 #define ST_ARG_COUNT() (stack[fp-4])
  40 #define ST_OLDFP() (stack[fp-1])
  41 #define ST_RET() (stack[fp-2])
  42 #define ST_ENV() (stack[fp-3])
  43 #define ST_FRMEND() (fp-4-stack[fp-4])
  44 #define RETURN() goto *pop()
  45
  46 /* General Purpose Registers */
  47 extern int* r;
  48 extern int r_res;
  49
  50 #endif