toka/vm.c

   1 /******************************************************
   2  * Toka
   3  *
   4  *|F|
   5  *|F| FILE: vm.c
   6  *|F|
   7  *
   8  * Copyright (c) 2006, 2007  Charles R. Childers
   9  *
  10  * Permission to use, copy, modify, and distribute this
  11  * software for any purpose with or without fee is hereby
  12  * granted, provided that the above copyright notice and
  13  * this permission notice appear in all copies.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR
  16  * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE
  17  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
  18  * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE
  19  * FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
  20  * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
  21  * OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF
  22  * CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
  23  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
  24  * OF THIS SOFTWARE.
  25  ******************************************************/
  26
  27 #include <stdio.h>
  28 #include <stdlib.h>
  29
  30 #include "toka.h"
  31
  32
  33 /******************************************************
  34  *|F| Variables:
  35  *|F|   Inst *heap
  36  *|F|   Pointer into the current heap
  37  *|F|
  38  *|F|   Inst *ip
  39  *|F|   The instruction pointer
  40  *|F|
  41  *|F|   VM_STACK data, address, alternate
  42  *|F|   The data, address, and return stacks
  43  *|F|
  44  ******************************************************/
  45 Inst *heap, *ip;
  46 VM_STACK data, address, alternate;
  47
  48
  49 /******************************************************
  50  *|F| vm_init()
  51  *|F| Prepare the virtual machine. This sets up the
  52  *|F| stacks, and any other things that need to be
  53  *|F| initialized.
  54  *|F|
  55  ******************************************************/
  56 void vm_init()
  57 {
  58   data.stack = gc_alloc(MAX_DATA_STACK, sizeof(long), GC_KEEP);
  59   address.stack = gc_alloc(MAX_DATA_STACK, sizeof(long), GC_KEEP);
  60   alternate.stack = gc_alloc(MAX_DATA_STACK, sizeof(long), GC_KEEP);
  61
  62   data.sp = 0;
  63   address.sp = 0;
  64   alternate.sp = 0;
  65 }
  66
  67
  68 /******************************************************
  69  *|F| vm_run(Inst)
  70  *|F| Run through a list of instructions
  71  *|F| Side effects:
  72  *|F|   modifes *ip
  73  *|F|
  74  ******************************************************/
  75 void vm_run(Inst prog[])
  76 {
  77   ip = prog;
  78   while (*ip != 0)
  79   {
  80     vm_stack_check();
  81     ((*ip++)());
  82   }
  83 }
  84
  85
  86 /******************************************************
  87  *|F| vm_stack_check()
  88  *|F| Check for over/underflow and reset if detected
  89  *|F| If the return stack over/underflows, exit Toka
  90  *|F|
  91  ******************************************************/
  92 void vm_stack_check()
  93 {
  94   if (data.sp < 0 || data.sp > MAX_DATA_STACK)
  95     error(ERROR_STACK);
  96   if ((address.sp < 0 || address.sp > MAX_RETURN_STACK) || (alternate.sp < 0 || alternate.sp > MAX_DATA_STACK))
  97     error(ERROR_STACK);
  98 }
  99
 100
 101 /******************************************************
 102  *|F| vm_push(long a)
 103  *|F| Push a number to the stack.
 104  *|F|
 105  ******************************************************/
 106 void vm_push(long a)
 107 {
 108   data.sp++; TOS = a;
 109 }
 110
 111
 112 /******************************************************
 113  *|F| vm_lit()
 114  *|F| Push the value in the following memory location
 115  *|F| to the stack
 116  *|F|
 117  ******************************************************/
 118 void vm_lit()
 119 {
 120   vm_push((long)*ip++);
 121 }
 122
 123
 124 /******************************************************
 125  *|F| vm_quote_lit()
 126  *|F| Push the value in the following memory location
 127  *|F| to the stack
 128  *|F|
 129  ******************************************************/
 130 void vm_quote_lit()
 131 {
 132   vm_push((long)*ip++);
 133 }
 134
 135
 136 /******************************************************
 137  *|F| vm_string_lit()
 138  *|F| Push the pointer in the following memory location
 139  *|F| to the stack. This is a helper function for
 140  *|F| strings.
 141  *|F|
 142  ******************************************************/
 143 void vm_string_lit()
 144 {
 145   vm_push((long)*ip++);
 146 }
 147
 148
 149 /******************************************************
 150  *|F| vm_primitive()
 151  *|F| Invoke the primitive id # specified in the
 152  *|F| following cell.
 153  ******************************************************/
 154 void vm_primitive()
 155 {
 156   Inst xt;
 157   xt = (Inst )*ip++;
 158   ((xt)());
 159 }