src/runtime/dynbind.c

   1 /*
   2  * support for dynamic binding from C
   3  */
   4
   5 /*
   6  * This software is part of the SBCL system. See the README file for
   7  * more information.
   8  *
   9  * This software is derived from the CMU CL system, which was
  10  * written at Carnegie Mellon University and released into the
  11  * public domain. The software is in the public domain and is
  12  * provided with absolutely no warranty. See the COPYING and CREDITS
  13  * files for more information.
  14  */
  15
  16 #include "runtime.h"
  17 #include "sbcl.h"
  18 #include "globals.h"
  19 #include "dynbind.h"
  20
  21 #if defined(__i386__)
  22 #define GetBSP() ((struct binding *)SymbolValue(BINDING_STACK_POINTER))
  23 #define SetBSP(value) SetSymbolValue(BINDING_STACK_POINTER, (lispobj)(value))
  24 #else
  25 #define GetBSP() ((struct binding *)current_binding_stack_pointer)
  26 #define SetBSP(value) (current_binding_stack_pointer=(lispobj *)(value))
  27 #endif
  28
  29 void bind_variable(lispobj symbol, lispobj value)
  30 {
  31         lispobj old_value;
  32         struct binding *binding;
  33
  34         old_value = SymbolValue(symbol);
  35         binding = GetBSP();
  36         SetBSP(binding+1);
  37
  38         binding->value = old_value;
  39         binding->symbol = symbol;
  40         SetSymbolValue(symbol, value);
  41 }
  42
  43 void
  44 unbind(void)
  45 {
  46         struct binding *binding;
  47         lispobj symbol;
  48
  49         binding = GetBSP() - 1;
  50
  51         symbol = binding->symbol;
  52
  53         SetSymbolValue(symbol, binding->value);
  54
  55         binding->symbol = 0;
  56
  57         SetBSP(binding);
  58 }
  59
  60 void
  61 unbind_to_here(lispobj *bsp)
  62 {
  63     struct binding *target = (struct binding *)bsp;
  64     struct binding *binding = GetBSP();
  65     lispobj symbol;
  66
  67     while (target < binding) {
  68         binding--;
  69
  70         symbol = binding->symbol;
  71
  72         if (symbol) {
  73             SetSymbolValue(symbol, binding->value);
  74             binding->symbol = 0;
  75         }
  76
  77     }
  78     SetBSP(binding);
  79 }