helpers.c

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/* LIBDGL -- a Directed Graph Library implementation
 * SPDX-FileCopyrightText: 2002 Roberto Micarelli
 * SPDX-FileCopyrightText: GRASS Development Team
 * SPDX-License-Identifier: GPL-2.0-or-later
 */
 
/*
 * best view with tabstop=4
 */
 
#include <stdlib.h>
#include <string.h>
 
#include "type.h"
#include "tree.h"
#include "graph.h"
#include "helpers.h"
 
/*
 * helpers for parametric stack
 */
unsigned char *dgl_mempush(unsigned char *pstack, long *istack, long size,
                           void *pv)
{
    if (*istack == 0)
        pstack = NULL;
    pstack = realloc(pstack, size * (1 + *istack));
    if (pstack == NULL)
        return NULL;
    memcpy(&pstack[(*istack) * size], pv, size);
    (*istack)++;
    return pstack;
}
 
unsigned char *dgl_mempop(unsigned char *pstack, long *istack, long size)
{
    if (*istack == 0)
        return NULL;
    return &pstack[size * (--(*istack))];
}
 
void dgl_swapInt32Bytes(dglInt32_t *pn)
{
    unsigned char *pb = (unsigned char *)pn;
 
    pb[0] ^= pb[3];
    pb[3] ^= pb[0];
    pb[0] ^= pb[3];
 
    pb[1] ^= pb[2];
    pb[2] ^= pb[1];
    pb[1] ^= pb[2];
}
 
void dgl_swapInt64Bytes(dglInt64_t *pn)
{
    unsigned char *pb = (unsigned char *)pn;
 
    pb[0] ^= pb[7];
    pb[7] ^= pb[0];
    pb[0] ^= pb[7];
 
    pb[1] ^= pb[6];
    pb[6] ^= pb[1];
    pb[1] ^= pb[6];
 
    pb[2] ^= pb[5];
    pb[5] ^= pb[2];
    pb[2] ^= pb[5];
 
    pb[3] ^= pb[4];
    pb[4] ^= pb[3];
    pb[3] ^= pb[4];
}
 
/*
 * Keep the edge cost prioritizer in sync
 */
int dgl_edge_prioritizer_del(dglGraph_s *pG, dglInt32_t nId, dglInt32_t nPriId)
{
    dglTreeEdgePri32_s findPriItem, *pPriItem;
    register int iEdge1, iEdge2;
    dglInt32_t *pnNew;
 
    if (pG->edgePrioritizer.pvAVL) {
 
        findPriItem.nKey = nPriId;
        pPriItem = avl_find(pG->edgePrioritizer.pvAVL, &findPriItem);
 
        if (pPriItem && pPriItem->pnData) {
 
            pnNew = malloc(sizeof(dglInt32_t) * pPriItem->cnData);
 
            if (pnNew == NULL) {
                pG->iErrno = DGL_ERR_MemoryExhausted;
                return -pG->iErrno;
            }
 
            for (iEdge1 = 0, iEdge2 = 0; iEdge2 < pPriItem->cnData; iEdge2++) {
                if (pPriItem->pnData[iEdge2] != nId) {
                    pnNew[iEdge1++] = pPriItem->pnData[iEdge2];
                }
            }
 
            free(pPriItem->pnData);
            if (iEdge1 == 0) {
                free(pnNew);
                pPriItem->pnData = NULL;
                pPriItem->cnData = 0;
            }
            else {
                pPriItem->pnData = pnNew;
                pPriItem->cnData = iEdge1;
            }
        }
    }
    return 0;
}
 
int dgl_edge_prioritizer_add(dglGraph_s *pG, dglInt32_t nId, dglInt32_t nPriId)
{
    dglTreeEdgePri32_s *pPriItem;
 
    if (pG->edgePrioritizer.pvAVL == NULL) {
        pG->edgePrioritizer.pvAVL =
            avl_create(dglTreeEdgePri32Compare, NULL, dglTreeGetAllocator());
        if (pG->edgePrioritizer.pvAVL == NULL) {
            pG->iErrno = DGL_ERR_MemoryExhausted;
            return -pG->iErrno;
        }
    }
    pPriItem = dglTreeEdgePri32Add(pG->edgePrioritizer.pvAVL, nPriId);
    if (pPriItem == NULL) {
        pG->iErrno = DGL_ERR_MemoryExhausted;
        return -pG->iErrno;
    }
    if (pPriItem->cnData == 0) {
        pPriItem->pnData = (dglInt32_t *)malloc(sizeof(dglInt32_t));
    }
    else {
        pPriItem->pnData = (dglInt32_t *)realloc(
            pPriItem->pnData, sizeof(dglInt32_t) * (pPriItem->cnData + 1));
    }
    if (pPriItem->pnData == NULL) {
        pG->iErrno = DGL_ERR_MemoryExhausted;
        return -pG->iErrno;
    }
    pPriItem->pnData[pPriItem->cnData] = nId;
    pPriItem->cnData++;
    return 0;
}