262 lines
4.8 KiB
C
262 lines
4.8 KiB
C
/* Copyright (C) 2016 Jeremiah Orians
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* This file is part of stage0.
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*
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* stage0 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 3 of the License, or
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* (at your option) any later version.
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*
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* stage0 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 stage0. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "lisp.h"
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/* Deal with the fact GCC converts the 1 to the size of the structs being iterated over */
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#define CELL_SIZE 1
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//CONSTANT CELL_SIZE 16
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struct cell *free_cells;
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struct cell *gc_block_start;
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struct cell *top_allocated;
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void update_remaining()
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{
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int count = 0;
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struct cell* i = free_cells;
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while(NULL != i)
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{
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count = count + 1;
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i = i->cdr;
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}
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left_to_take = count;
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}
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struct cell* insert_ordered(struct cell* i, struct cell* list)
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{
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if(NULL == list)
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{
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return i;
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}
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if(i < list)
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{
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i->cdr = list;
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return i;
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}
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list->cdr = insert_ordered(i, list->cdr);
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return list;
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}
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void reclaim_marked()
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{
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struct cell* i;
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for(i= top_allocated; i >= gc_block_start ; i = i - CELL_SIZE)
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{
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if(i->type & MARKED)
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{
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i->type = FREE;
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i->car = NULL;
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i->cdr = NULL;
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i->env = NULL;
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free_cells = insert_ordered(i, free_cells);
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}
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}
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}
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void relocate_cell(struct cell* current, struct cell* target, struct cell* list)
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{
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for(; NULL != list; list = list->cdr)
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{
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if(list->car == current)
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{
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list->car = target;
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}
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if(list->cdr == current)
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{
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list->cdr = target;
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}
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if(list->env == current)
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{
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list->env = target;
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}
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if((list->type & CONS)|| list->type & PROC )
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{
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relocate_cell(current, target, list->car);
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}
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}
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}
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struct cell* pop_cons();
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void compact(struct cell* list)
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{
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for(; NULL != list; list = list->cdr)
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{
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if((FREE != list->type) && (list > free_cells ))
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{
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struct cell* temp = pop_cons();
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temp->type = list->type;
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temp->car = list->car;
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temp->cdr = list->cdr;
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temp->env = list->env;
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relocate_cell(list, temp, all_symbols);
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relocate_cell(list, temp, top_env);
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}
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if((list->type & CONS)|| list->type & PROC )
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{
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compact(list->car);
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}
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}
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}
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void mark_all_cells()
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{
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struct cell* i;
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for(i= gc_block_start; i < top_allocated; i = i + CELL_SIZE)
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{
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/* if not in the free list */
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if(!(i->type & FREE))
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{
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/* Mark it */
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i->type = i->type | MARKED;
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}
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}
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}
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void unmark_cells(struct cell* list, struct cell* stop, int count)
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{
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if(count > 1) return;
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for(; NULL != list; list = list->cdr)
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{
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if(list == stop) count = count + 1;
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list->type = list->type & ~MARKED;
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if(list->type & PROC)
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{
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unmark_cells(list->car, stop, count);
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if(NULL != list->env)
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{
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unmark_cells(list->env, stop, count);
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}
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}
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if(list->type & CONS)
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{
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unmark_cells(list->car, stop, count);
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}
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}
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}
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void garbage_collect()
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{
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mark_all_cells();
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unmark_cells(current, current, 0);
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unmark_cells(all_symbols, all_symbols, 0);
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unmark_cells(top_env, top_env, 0);
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reclaim_marked();
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update_remaining();
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compact(all_symbols);
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compact(top_env);
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top_allocated = NULL;
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}
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void garbage_init(int number_of_cells)
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{
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gc_block_start = calloc(number_of_cells + 1, sizeof(struct cell));
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top_allocated = gc_block_start + number_of_cells;
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free_cells = NULL;
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garbage_collect();
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top_allocated = NULL;
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}
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struct cell* pop_cons()
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{
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if(NULL == free_cells)
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{
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file_print("OOOPS we ran out of cells", stderr);
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exit(EXIT_FAILURE);
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}
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struct cell* i;
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i = free_cells;
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free_cells = i->cdr;
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i->cdr = NULL;
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if(i > top_allocated)
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{
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top_allocated = i;
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}
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left_to_take = left_to_take - 1;
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return i;
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}
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struct cell* make_cell(int type, struct cell* a, struct cell* b, struct cell* env)
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{
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struct cell* c = pop_cons();
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c->type = type;
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c->car = a;
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c->cdr = b;
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c->env = env;
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return c;
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}
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struct cell* make_int(int a)
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{
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struct cell* c = pop_cons();
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c->type = INT;
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c->value = a;
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return c;
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}
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struct cell* make_char(int a)
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{
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struct cell* c = pop_cons();
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c->type = CHAR;
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c->value = a;
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return c;
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}
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struct cell* make_string(char* a)
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{
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struct cell* c = pop_cons();
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c->type = STRING;
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c->string = a;
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return c;
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}
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struct cell* make_sym(char* name)
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{
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struct cell* c = pop_cons();
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c->type = SYM;
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c->string = name;
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return c;
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}
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struct cell* make_cons(struct cell* a, struct cell* b)
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{
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return make_cell(CONS, a, b, nil);
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}
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struct cell* make_proc(struct cell* a, struct cell* b, struct cell* env)
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{
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return make_cell(PROC, a, b, env);
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}
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struct cell* make_prim(void* fun)
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{
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struct cell* c = pop_cons();
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c->type = PRIMOP;
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c->function = fun;
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return c;
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}
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