src/lisp/dynbind.c

   1 /*
   2  * Support for dynamic binding from C.
   3  */
   4
   5 #include "lisp.h"
   6 #include "internals.h"
   7 #include "globals.h"
   8 #include "dynbind.h"
   9
  10 #if defined(ibmrt) || defined(i386) || defined(__x86_64)
  11 #define GetBSP() ((struct binding *)SymbolValue(BINDING_STACK_POINTER))
  12 #define SetBSP(value) SetSymbolValue(BINDING_STACK_POINTER, (lispobj)(value))
  13 #else
  14 #define GetBSP() ((struct binding *)current_binding_stack_pointer)
  15 #define SetBSP(value) (current_binding_stack_pointer=(lispobj *)(value))
  16 #endif
  17
  18 void
  19 bind_variable(lispobj symbol, lispobj value)
  20 {
  21     lispobj old_value;
  22     struct binding *binding;
  23
  24     old_value = SymbolValue(symbol);
  25     binding = GetBSP();
  26     SetBSP(binding + 1);
  27
  28     binding->value = old_value;
  29     binding->symbol = symbol;
  30     SetSymbolValue(symbol, value);
  31 }
  32
  33 void
  34 unbind(void)
  35 {
  36     struct binding *binding;
  37     lispobj symbol;
  38
  39     binding = GetBSP() - 1;
  40
  41     symbol = binding->symbol;
  42
  43     SetSymbolValue(symbol, binding->value);
  44
  45     binding->symbol = 0;
  46
  47     SetBSP(binding);
  48 }
  49
  50 void
  51 unbind_to_here(lispobj * bsp)
  52 {
  53     struct binding *target = (struct binding *) bsp;
  54     struct binding *binding = GetBSP();
  55     lispobj symbol;
  56
  57     while (target < binding) {
  58         binding--;
  59
  60         symbol = binding->symbol;
  61
  62         if (symbol) {
  63             SetSymbolValue(symbol, binding->value);
  64             binding->symbol = 0;
  65         }
  66
  67     }
  68     SetBSP(binding);
  69 }