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/* |
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stack - an interactive interpreter for a stack-based language |
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Copyright (C) 2002 Mats Alritzson and Teddy Hogeborn |
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|
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This program is free software; you can redistribute it and/or modify |
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it under the terms of the GNU General Public License as published by |
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the Free Software Foundation; either version 2 of the License, or |
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(at your option) any later version. |
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|
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This program is distributed in the hope that it will be useful, |
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but WITHOUT ANY WARRANTY; without even the implied warranty of |
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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GNU General Public License for more details. |
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|
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You should have received a copy of the GNU General Public License |
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along with this program; if not, write to the Free Software |
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA |
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|
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Authors: Mats Alritzson <masse@fukt.bth.se> |
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Teddy Hogeborn <teddy@fukt.bth.se> |
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*/ |
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|
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#include "stack.h" |
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|
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/* Mark values recursively. |
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Marked values are not collected by the GC. */ |
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inline void gc_mark(value *val) |
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{ |
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if(val==NULL || val->gc.flag.mark) |
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return; |
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|
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val->gc.flag.mark= 1; |
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|
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if(val->type==tcons) { |
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gc_mark(CAR(val)); |
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gc_mark(CDR(val)); |
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} |
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} |
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|
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|
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/* Start GC */ |
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extern void gc_init(environment *env) |
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{ |
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stackitem *new_head= NULL, *titem; |
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symbol *tsymb; |
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int i; |
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|
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if(env->interactive) |
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printf("Garbage collecting."); |
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|
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/* Mark values on stack */ |
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gc_mark(env->head); |
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|
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if(env->interactive) |
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printf("."); |
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|
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/* Mark values in hashtable */ |
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for(i= 0; i<HASHTBLSIZE; i++) |
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for(tsymb= env->symbols[i]; tsymb!=NULL; tsymb= tsymb->next) |
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if (tsymb->val != NULL) |
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gc_mark(tsymb->val); |
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|
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if(env->interactive) |
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printf("."); |
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|
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env->gc_count= 0; |
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|
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while(env->gc_ref!=NULL) { /* Sweep unused values */ |
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if(!(env->gc_ref->item->gc.no_gc)){ /* neither mark nor protect */ |
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|
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/* Remove content */ |
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switch(env->gc_ref->item->type){ |
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case string: |
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free(env->gc_ref->item->content.string); |
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break; |
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case tcons: |
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free(env->gc_ref->item->content.c); |
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break; |
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case port: |
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case empty: |
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case unknown: |
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case integer: |
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case tfloat: |
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case func: |
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case symb: |
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/* Symbol strings are freed when walking the hash table */ |
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break; |
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} |
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|
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free(env->gc_ref->item); /* Remove from gc_ref */ |
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titem= env->gc_ref->next; |
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free(env->gc_ref); /* Remove value */ |
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env->gc_ref= titem; |
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continue; |
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} |
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|
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#ifdef DEBUG |
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printf("Kept value (%p)", env->gc_ref->item); |
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if(env->gc_ref->item->gc.flag.mark) |
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printf(" (marked)"); |
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if(env->gc_ref->item->gc.flag.protect) |
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printf(" (protected)"); |
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switch(env->gc_ref->item->type){ |
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case integer: |
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printf(" integer: %d", env->gc_ref->item->content.i); |
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break; |
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case func: |
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printf(" func: %p", env->gc_ref->item->content.func); |
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break; |
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case symb: |
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printf(" symb: %s", env->gc_ref->item->content.sym->id); |
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break; |
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case tcons: |
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printf(" tcons: %p\t%p", CAR(env->gc_ref->item), |
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CDR(env->gc_ref->item)); |
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break; |
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default: |
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printf(" <unknown %d>", (env->gc_ref->item->type)); |
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} |
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printf("\n"); |
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#endif /* DEBUG */ |
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|
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/* Keep values */ |
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env->gc_count += sizeof(value); |
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if(env->gc_ref->item->type==string) |
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env->gc_count += strlen(env->gc_ref->item->content.string)+1; |
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|
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titem= env->gc_ref->next; |
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env->gc_ref->next= new_head; |
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new_head= env->gc_ref; |
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new_head->item->gc.flag.mark= 0; |
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env->gc_ref= titem; |
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} |
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|
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if (env->gc_limit < env->gc_count*2) |
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env->gc_limit= env->gc_count*2; |
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|
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env->gc_ref= new_head; |
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|
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if(env->interactive) |
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printf("done (%d bytes still allocated)\n", env->gc_count); |
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|
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} |
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|
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|
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inline void gc_maybe(environment *env) |
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{ |
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if(env->gc_count < env->gc_limit) |
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return; |
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else |
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return gc_init(env); |
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} |
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|
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|
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/* Protect values from GC */ |
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void protect(value *val) |
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{ |
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if(val==NULL || val->gc.flag.protect) |
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return; |
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|
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val->gc.flag.protect= 1; |
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|
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if(val->type==tcons) { |
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protect(CAR(val)); |
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protect(CDR(val)); |
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} |
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} |
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|
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|
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/* Unprotect values from GC */ |
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void unprotect(value *val) |
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{ |
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if(val==NULL || !(val->gc.flag.protect)) |
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return; |
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|
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val->gc.flag.protect= 0; |
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|
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if(val->type==tcons) { |
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unprotect(CAR(val)); |
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unprotect(CDR(val)); |
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} |
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} |
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