src/runtime/dynbind.c

   1 /*
   2  * support for dynamic binding from C
   3  * See the "Chapter 9: Specials" of the SBCL Internals Manual.
   4  */
   5
   6 /*
   7  * This software is part of the SBCL system. See the README file for
   8  * more information.
   9  *
  10  * This software is derived from the CMU CL system, which was
  11  * written at Carnegie Mellon University and released into the
  12  * public domain. The software is in the public domain and is
  13  * provided with absolutely no warranty. See the COPYING and CREDITS
  14  * files for more information.
  15  */
  16
  17 #include <stdio.h>
  18 #include <stdlib.h>
  19
  20 #include "sbcl.h"
  21 #include "runtime.h"
  22 #include "globals.h"
  23 #include "dynbind.h"
  24 #include "thread.h"
  25 #include "interr.h"
  26 #include "genesis/symbol.h"
  27 #include "genesis/binding.h"
  28
  29 /* Specially bind SYMBOL to VALUE. In a multithreaded build, SYMBOL must already
  30    have been assigned a thread-local storage index. See *KNOWN-TLS-SYMBOLS* in
  31    compiler/generic/genesis for the symbols whose indices are pre-assigned. */
  32 #ifdef LISP_FEATURE_SB_THREAD
  33 #define value_address(thing, thread) \
  34   (lispobj*)(thing + (char*)((union per_thread_data *)thread)->dynamic_values)
  35 void bind_tls_cell(unsigned symbol, lispobj value, void *th)
  36 #else
  37 #define value_address(thing, thread) &SYMBOL(thing)->value
  38 void bind_variable(lispobj symbol, lispobj value, void *th)
  39 #endif
  40 {
  41     struct binding *binding;
  42     __attribute__((unused)) struct thread *thread = (struct thread *)th;
  43     binding = (struct binding *)get_binding_stack_pointer(thread);
  44     set_binding_stack_pointer(thread,binding+1);
  45     binding->symbol = symbol;
  46     lispobj* where = value_address(symbol, thread);
  47     binding->value = *where;
  48     *where = value;
  49 }
  50
  51 void
  52 unbind(void *th)
  53 {
  54      __attribute__((unused)) struct thread *thread = (struct thread *)th;
  55     struct binding *binding;
  56
  57     binding = ((struct binding *)get_binding_stack_pointer(thread)) - 1;
  58
  59     /* On sb-thread, 'binding->symbol' is actually a tls-index */
  60     *value_address(binding->symbol, thread) = binding->value;
  61
  62     binding->symbol = 0;
  63     binding->value = 0;
  64
  65     set_binding_stack_pointer(thread,binding);
  66 }
  67
  68 void
  69 unbind_to_here(lispobj *bsp,void *th)
  70 {
  71      __attribute__((unused)) struct thread *thread = (struct thread *)th;
  72     struct binding *target = (struct binding *)bsp;
  73     struct binding *binding = (struct binding *)get_binding_stack_pointer(thread);
  74     lispobj symbol;
  75
  76     while (target < binding) {
  77         binding--;
  78
  79         symbol = binding->symbol;
  80         if (symbol) {
  81             if (symbol != UNBOUND_MARKER_WIDETAG) {
  82                 *value_address(symbol, thread) = binding->value;
  83             }
  84             binding->symbol = 0;
  85             binding->value = 0;
  86         }
  87     }
  88     set_binding_stack_pointer(thread,binding);
  89 }