140 lines
3.2 KiB
C
140 lines
3.2 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include "segtab.h"
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struct segtabnode {
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int localseg;
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int destseg;
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int32_t offset;
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struct segtabnode *left;
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struct segtabnode *right;
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/*
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* counts of how many are left or right, for use in reorganising
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* the tree
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*/
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int leftcount;
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int rightcount;
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};
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/*
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* init_seglocations()
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* add_seglocation()
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* get_seglocation()
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* done_seglocation()
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*
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* functions used by write_output() to manipulate associations
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* between segment numbers and locations (which are built up on a per
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* module basis, but we only need one module at a time...)
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*
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* implementation: we build a binary tree.
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*/
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void init_seglocations(segtab * root)
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{
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*root = NULL;
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}
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void descend_tree_add(struct segtabnode **node,
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int localseg, int destseg, int32_t offset)
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{
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struct segtabnode *n;
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if (*node == NULL) {
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*node = malloc(sizeof(**node));
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if (!*node) {
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fprintf(stderr, "segment table: out of memory\n");
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exit(1);
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}
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(*node)->localseg = localseg;
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(*node)->offset = offset;
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(*node)->left = NULL;
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(*node)->leftcount = 0;
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(*node)->right = NULL;
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(*node)->rightcount = 0;
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(*node)->destseg = destseg;
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return;
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}
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if (localseg < (*node)->localseg) {
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(*node)->leftcount++;
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descend_tree_add(&(*node)->left, localseg, destseg, offset);
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if ((*node)->leftcount > (*node)->rightcount + 2) {
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n = *node;
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*node = n->left;
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n->left = (*node)->right;
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n->leftcount = (*node)->rightcount;
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(*node)->right = n;
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(*node)->rightcount = n->leftcount + n->rightcount + 1;
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}
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} else {
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(*node)->rightcount++;
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descend_tree_add(&(*node)->right, localseg, destseg, offset);
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if ((*node)->rightcount > (*node)->leftcount + 2) {
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n = *node;
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*node = n->right;
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n->right = (*node)->left;
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n->rightcount = (*node)->leftcount;
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(*node)->left = n;
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(*node)->leftcount = n->leftcount + n->rightcount + 1;
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}
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}
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}
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void add_seglocation(segtab * root, int localseg, int destseg, int32_t offset)
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{
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descend_tree_add((struct segtabnode **)root, localseg, destseg,
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offset);
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}
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int get_seglocation(segtab * root, int localseg, int *destseg,
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int32_t *offset)
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{
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struct segtabnode *n = (struct segtabnode *)*root;
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while (n && n->localseg != localseg) {
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if (localseg < n->localseg)
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n = n->left;
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else
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n = n->right;
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}
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if (n) {
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*destseg = n->destseg;
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*offset = n->offset;
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return 1;
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} else
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return 0;
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}
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void freenode(struct segtabnode *n)
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{
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if (!n)
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return;
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freenode(n->left);
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freenode(n->right);
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free(n);
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}
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void done_seglocations(segtab * root)
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{
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freenode(*root);
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*root = NULL;
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}
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#if 0
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void printnode(int i, struct segtabnode *n)
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{
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if (!n)
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return;
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printnode(i + 1, n->left);
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printf("%*s%d %d %ld\n", i, "", n->localseg, n->destseg, n->offset);
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printnode(i + 1, n->right);
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}
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void printtable()
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{
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printnode(0, root);
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}
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#endif
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