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 #include "genesis/symbol.h"
  21 #include "genesis/binding.h"
  22 #include "genesis/static-symbols.h"
  23
  24 #if defined(__i386__)
  25 #define GetBSP() ((struct binding *)SymbolValue(BINDING_STACK_POINTER))
  26 #define SetBSP(value) SetSymbolValue(BINDING_STACK_POINTER, (lispobj)(value))
  27 #else
  28 #define GetBSP() ((struct binding *)current_binding_stack_pointer)
  29 #define SetBSP(value) (current_binding_stack_pointer=(lispobj *)(value))
  30 #endif
  31
  32 void bind_variable(lispobj symbol, lispobj value)
  33 {
  34     lispobj old_value;
  35     struct binding *binding;
  36
  37     old_value = SymbolValue(symbol);
  38     binding = GetBSP();
  39     SetBSP(binding+1);
  40
  41     binding->value = old_value;
  42     binding->symbol = symbol;
  43     SetSymbolValue(symbol, value);
  44 }
  45
  46 void
  47 unbind(void)
  48 {
  49     struct binding *binding;
  50     lispobj symbol;
  51
  52     binding = GetBSP() - 1;
  53
  54     symbol = binding->symbol;
  55
  56     SetSymbolValue(symbol, binding->value);
  57
  58     binding->symbol = 0;
  59
  60     SetBSP(binding);
  61 }
  62
  63 void
  64 unbind_to_here(lispobj *bsp)
  65 {
  66     struct binding *target = (struct binding *)bsp;
  67     struct binding *binding = GetBSP();
  68     lispobj symbol;
  69
  70     while (target < binding) {
  71         binding--;
  72
  73         symbol = binding->symbol;
  74
  75         if (symbol) {
  76             SetSymbolValue(symbol, binding->value);
  77             binding->symbol = 0;
  78         }
  79
  80     }
  81     SetBSP(binding);
  82 }