/****************************************************************************** libpammap.c ******************************************************************************* These are functions that deal with tuple hashes and tuple tables. Both tuple hashes and tuple tables let you associate an arbitrary integer with a tuple value. A tuple hash lets you look up the one integer value (if any) associated with a given tuple value, having the low memory and execution time characteristics of a hash table. A tuple table lets you scan all the values, being a table of elements that consist of an ordered pair of a tuple value and integer. ******************************************************************************/ #include "pam.h" #include "pammap.h" #define HASH_SIZE 20023 unsigned int pnm_hashtuple(struct pam * const pamP, tuple const tuple) { /*---------------------------------------------------------------------------- Return the hash value of the tuple 'tuple' -- i.e. an index into a hash table. -----------------------------------------------------------------------------*/ int i; unsigned int hash; const unsigned int hash_factor[] = {33023, 30013, 27011}; hash = 0; /* initial value */ for (i = 0; i < MIN(pamP->depth, 3); ++i) { hash += tuple[i] * hash_factor[i]; /* May overflow */ } hash %= HASH_SIZE; return hash; } tuplehash pnm_createtuplehash(void) { /*---------------------------------------------------------------------------- Create an empty tuple hash -- i.e. a hash table of zero length hash chains. -----------------------------------------------------------------------------*/ tuplehash const retval = malloc(HASH_SIZE * sizeof(tupleint_list)); unsigned int i; for (i = 0; i < HASH_SIZE; ++i) retval[i] = NULL; return retval; } void pnm_destroytuplehash(tuplehash const tuplehash) { int i; /* Free the chains */ for (i = 0; i < HASH_SIZE; ++i) { struct tupleint_list_item * p; struct tupleint_list_item * next; /* Walk this chain, freeing each element */ for (p = tuplehash[i]; p; p = next) { next = p->next; free(p); } } /* Free the table of chains */ free(tuplehash); } static struct tupleint_list_item * allocTupleIntListItem(struct pam * const pamP) { /* This is complicated by the fact that the last element of a tupleint_list_item is of variable length, because the last element of _it_ is of variable length */ struct tupleint_list_item * retval; retval = (struct tupleint_list_item *) malloc(sizeof(*retval) - sizeof(retval->tupleint.tuple) + pamP->depth * sizeof(sample)); return retval; } void pnm_addtotuplehash(struct pam * const pamP, tuplehash const tuplehash, tuple const tupletoadd, int const value, int * const fitsP) { /*---------------------------------------------------------------------------- Add a tuple value to the hash -- assume it isn't already there. Allocate new space for the tuple value and the hash chain element. If we can't allocate space for the new hash chain element, don't change anything and return *fitsP = FALSE; -----------------------------------------------------------------------------*/ struct tupleint_list_item * const listItemP = allocTupleIntListItem(pamP); if (listItemP == NULL) *fitsP = FALSE; else { unsigned int const hashvalue = pnm_hashtuple(pamP, tupletoadd); *fitsP = TRUE; pnm_assigntuple(pamP, listItemP->tupleint.tuple, tupletoadd); listItemP->tupleint.value = value; listItemP->next = tuplehash[hashvalue]; tuplehash[hashvalue] = listItemP; } } void pnm_lookuptuple(struct pam * const pamP, const tuplehash tuplehash, const tuple searchval, int * const foundP, int * const retvalP) { unsigned int const hashvalue = pnm_hashtuple(pamP, searchval); struct tupleint_list_item * p; struct tupleint_list_item * found; found = NULL; /* None found yet */ for (p = tuplehash[hashvalue]; p && !found; p = p->next) if (pnm_tupleequal(pamP, p->tupleint.tuple, searchval)) { found = p; } if (found) { *foundP = TRUE; *retvalP = found->tupleint.value; } else *foundP = FALSE; } static void addColorToHash(tuple const color, tuplehash const tuplefreqhash, struct pam * const pamP, unsigned int const maxsize, unsigned int * const sizeP, bool * const fullP) { unsigned int const hashvalue = pnm_hashtuple(pamP, color); struct tupleint_list_item *p; for (p = tuplefreqhash[hashvalue]; p && !pnm_tupleequal(pamP, p->tupleint.tuple, color); p = p->next); if (p) { p->tupleint.value++; *fullP = FALSE; } else { /* It's not in the hash yet, so add it (if allowed) */ ++(*sizeP); if (maxsize > 0 && *sizeP > maxsize) *fullP = TRUE; else { *fullP = FALSE; p = allocTupleIntListItem(pamP); if (p == NULL) pm_error("out of memory computing hash table"); pnm_assigntuple(pamP, p->tupleint.tuple, color); p->tupleint.value = 1; p->next = tuplefreqhash[hashvalue]; tuplefreqhash[hashvalue] = p; } } } static tuplehash computetuplefreqhash(struct pam * const pamP, tuple ** const tupleArray, unsigned int const maxsize, sample const newMaxval, unsigned int * const sizeP) { /*---------------------------------------------------------------------------- Compute a tuple frequency hash from a PAM. This is a hash that gives you the number of times a given tuple value occurs in the PAM. You can supply the input PAM in one of two ways: 1) a two-dimensional array of tuples tupleArray[][]; In this case, 'tupleArray' is non-NULL. 2) an open PAM file, positioned to the raster. In this case, 'tupleArray' is NULL. *pamP contains the file descriptor. We return with the file still open and its position undefined. In either case, *pamP contains parameters of the tuple array. Return the number of unique tuple values found as *sizeP. However, if the number of unique tuple values is greater than 'maxsize', return a null return value and *sizeP undefined. -----------------------------------------------------------------------------*/ tuplehash tuplefreqhash; int row; tuple * rowbuffer; /* malloc'ed */ /* Buffer for a row read from the input file; undefined (but still allocated) if input is not from a file. */ tuple color; /* The color being current being added, scaled to the new maxval */ struct pam freqPam; bool full; freqPam = *pamP; freqPam.maxval = newMaxval; tuplefreqhash = pnm_createtuplehash(); *sizeP = 0; /* initial value */ rowbuffer = pnm_allocpamrow(pamP); color = pnm_allocpamtuple(&freqPam); full = FALSE; /* initial value */ /* Go through the entire raster, building a hash table of tuple values. */ for (row = 0; row < pamP->height && !full; ++row) { int col; const tuple * tuplerow; /* The row of tuples we are processing */ if (tupleArray) tuplerow = tupleArray[row]; else { pnm_readpamrow(pamP, rowbuffer); tuplerow = rowbuffer; } for (col = 0; col < pamP->width && !full; ++col) { pnm_scaletuple(pamP, color, tuplerow[col], freqPam.maxval); addColorToHash(color, tuplefreqhash, &freqPam, maxsize, sizeP, &full); } } pnm_freepamtuple(color); pnm_freepamrow(rowbuffer); if (full) { pnm_destroytuplehash(tuplefreqhash); return NULL; } else return tuplefreqhash; } tuplehash pnm_computetuplefreqhash(struct pam * const pamP, tuple ** const tupleArray, unsigned int const maxsize, unsigned int * const sizeP) { /*---------------------------------------------------------------------------- Compute the tuple frequency hash for the tuple array tupleArray[][]. -----------------------------------------------------------------------------*/ return computetuplefreqhash(pamP, tupleArray, maxsize, pamP->maxval, sizeP); } tupletable pnm_alloctupletable(const struct pam * const pamP, unsigned int const size) { unsigned int const tupleIntSize = sizeof(struct tupleint) - sizeof(sample) + pamP->depth * sizeof(sample); unsigned int const mainTableSize = size * sizeof(struct tupleint *); void * pool; tupletable retval; unsigned int i; /* To save the enormous amount of time it could take to allocate each individual tuple, we do a trick here and allocate everything as a single malloc block and suballocate internally. */ pool = malloc(mainTableSize + size * tupleIntSize); retval = (tupletable) pool; for (i = 0; i < size; ++i) retval[i] = (struct tupleint *) ((char*)pool + mainTableSize + i * tupleIntSize); return retval; } void pnm_freetupletable(struct pam * const pamP, tupletable const tupletable) { /* Note that the address 'tupletable' is, to the operating system, the address of a larger block of memory that contains not only tupletable, but all the samples to which it points (e.g. tupletable[0].tuple[0]) */ free(tupletable); } tupletable pnm_tuplehashtotable(const struct pam * const pamP, tuplehash const tuplehash, unsigned int const maxsize) { /*---------------------------------------------------------------------------- Create a tuple table containing the info from a tuple hash. Allocate space in the table for 'maxsize' elements even if there aren't that many tuple values in the input hash. That's so the caller has room for expansion. We allocate new space for all the table contents; there are no pointers in the table to tuples or anything else in existing space. -----------------------------------------------------------------------------*/ tupletable tupletable; int i, j; tupletable = pnm_alloctupletable(pamP, maxsize); if (tupletable == NULL) pm_error("out of memory generating tuple table"); /* Loop through the hash table. */ j = 0; for (i = 0; i < HASH_SIZE; ++i) { /* Walk this hash chain */ struct tupleint_list_item * p; for (p = tuplehash[i]; p; p = p->next) { tupletable[j]->value = p->tupleint.value; pnm_assigntuple(pamP, tupletable[j]->tuple, p->tupleint.tuple); ++j; } } return tupletable; } tuplehash pnm_computetupletablehash(struct pam * const pamP, tupletable const tupletable, unsigned int const tupletableSize) { /*---------------------------------------------------------------------------- Create a tuple hash containing indices into the tuple table 'tupletable'. The hash index for the hash is the value of a tuple; the hash value is the tuple table index for the element in the tuple table that contains that tuple value. Assume there are no duplicate tuple values in the tuple table. We allocate space for the main hash table and all the elements of the hash chains. -----------------------------------------------------------------------------*/ tuplehash tupletablehash; unsigned int i; tupletablehash = pnm_createtuplehash(); for (i = 0; i < tupletableSize; ++i) { bool fits; pnm_addtotuplehash(pamP, tupletablehash, tupletable[i]->tuple, i, &fits); if (!fits) pm_error("Out of memory computing tuple hash from tuple table"); } return tupletablehash; } tupletable pnm_computetuplefreqtable2(struct pam * const pamP, tuple ** const tupleArray, unsigned int const maxsize, sample const newMaxval, unsigned int * const sizeP) { /*---------------------------------------------------------------------------- Compute the a tuple frequency table from a PAM image. This is an array that tells how many times each tuple value occurs in the image. Except for the format of the output, this function is the same as computetuplefreqhash(). Return the array in newly malloc'ed storage. Allocate space for 'maxsize' entries even if there aren't that many colors in tupleArray[]. That's so the caller has room for expansion. Return the number of unique tuple values in tupleArray[][], which is the size of the output array, as *sizeP. If there are more than 'maxsize' unique tuple values in tupleArray[][], give up. -----------------------------------------------------------------------------*/ tuplehash tuplefreqhash; tupletable tuplefreqtable; tuplefreqhash = computetuplefreqhash(pamP, tupleArray, maxsize, newMaxval, sizeP); if (tuplefreqhash == NULL) tuplefreqtable = NULL; else { tuplefreqtable = pnm_tuplehashtotable(pamP, tuplefreqhash, maxsize); pnm_destroytuplehash(tuplefreqhash); } return tuplefreqtable; } tupletable pnm_computetuplefreqtable(struct pam * const pamP, tuple ** const tupleArray, unsigned int const maxsize, unsigned int * const sizeP) { return pnm_computetuplefreqtable2(pamP, tupleArray, maxsize, pamP->maxval, sizeP); } char* pam_colorname(struct pam * const pamP, tuple const color, enum colornameFormat const format) { unsigned int r, g, b; FILE* f; static char colorname[200]; r = pnm_scalesample(color[PAM_RED_PLANE], pamP->maxval, 255); g = pnm_scalesample(color[PAM_GRN_PLANE], pamP->maxval, 255); b = pnm_scalesample(color[PAM_BLU_PLANE], pamP->maxval, 255); f = pm_openColornameFile(NULL, format == PAM_COLORNAME_ENGLISH); if (f != NULL) { unsigned int best_diff; bool done; best_diff = 32767; done = FALSE; while (!done) { struct colorfile_entry const ce = pm_colorget(f); if (ce.colorname) { unsigned int const this_diff = abs((int)r - (int)ce.r) + abs((int)g - (int)ce.g) + abs((int)b - (int)ce.b); if (this_diff < best_diff) { best_diff = this_diff; strcpy(colorname, ce.colorname); } } else done = TRUE; } fclose(f); if (best_diff != 32767 && (best_diff == 0 || format == PAM_COLORNAME_ENGLISH)) return colorname; } /* Color lookup failed, but caller is willing to take an X11-style hex specifier, so return that. */ sprintf(colorname, "#%02x%02x%02x", r, g, b); return colorname; }