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Annotation of 43BSD/contrib/X/Xlib/XMakeAssoc.c, revision 1.1

1.1     ! root        1: #include <X/mit-copyright.h>
        !             2: 
        !             3: /* $Header: XMakeAssoc.c,v 10.4 86/02/01 15:36:32 tony Rel $ */
        !             4: /* Copyright    Massachusetts Institute of Technology    1985  */
        !             5: 
        !             6: #include "XlibInternal.h"
        !             7: 
        !             8: /*
        !             9:  * XMakeAssoc - Insert data into an XAssocTable keyed on an XId.
        !            10:  * Data is inserted into the table only once.  Redundant inserts are
        !            11:  * meaningless (but cause no problems).  The queue in each association
        !            12:  * bucket is sorted (lowest XId to highest XId).
        !            13:  */
        !            14: XMakeAssoc(table, x_id, data)
        !            15:        register XAssocTable *table;
        !            16:        register XId x_id;
        !            17:        register caddr_t data;
        !            18: {
        !            19:        int hash;
        !            20:        register XAssoc *bucket;
        !            21:        register XAssoc *entry;
        !            22:        register XAssoc *new_entry;
        !            23:        
        !            24:        /* Hash the XId to get the bucket number. */
        !            25:        hash = x_id & (table->size - 1);
        !            26:        /* Look up the bucket to get the entries in that bucket. */
        !            27:        bucket = &(*table->table)[hash];
        !            28:        /* Get the first entry in the bucket. */
        !            29:        entry = bucket->next;
        !            30: 
        !            31:        /* If (entry != bucket), the bucket is empty so make */
        !            32:        /* the new entry the first entry in the bucket. */
        !            33:        /* if (entry == bucket), the we have to search the */
        !            34:        /* bucket. */
        !            35:        if (entry != bucket) {
        !            36:                /* The bucket isn't empty, begin searching. */
        !            37:                /* If we leave the for loop then we have either passed */
        !            38:                /* where the entry should be or hit the end of the bucket. */
        !            39:                /* In either case we should then insert the new entry */
        !            40:                /* before the current value of "entry". */
        !            41:                for (entry; entry != bucket; entry = entry->next) {
        !            42:                        if (entry->x_id == x_id) {
        !            43:                                /* Entry has the same XId... */
        !            44:                                if (entry->display == _XlibCurrentDisplay) {
        !            45:                                        /* Entry has the same Display... */
        !            46:                                        /* Therefore there is already an */
        !            47:                                        /* entry with this XId and Display, */
        !            48:                                        /* reset its data value and return. */
        !            49:                                        entry->data = data;
        !            50:                                        return;
        !            51:                                }
        !            52:                                /* We found an association with the right */
        !            53:                                /* id but the wrong display! */
        !            54:                                continue;
        !            55:                        }
        !            56:                        /* If the current entry's XId is greater than the */
        !            57:                        /* XId of the entry to be inserted then we have */
        !            58:                        /* passed the location where the new XId should */
        !            59:                        /* be inserted. */
        !            60:                        if (entry->x_id > x_id) break;
        !            61:                }
        !            62:         }
        !            63: 
        !            64:        /* If we are here then the new entry should be inserted just */
        !            65:        /* before the current value of "entry". */
        !            66:        /* Create a new XAssoc and load it with new provided data. */
        !            67:        new_entry = (XAssoc *)malloc(sizeof(XAssoc));
        !            68:        if (new_entry == NULL) {
        !            69:                /* Malloc failed! */
        !            70:                errno = ENOMEM;
        !            71:                _XIOError(_XlibCurrentDisplay);
        !            72:        }
        !            73:        new_entry->display = _XlibCurrentDisplay;
        !            74:        new_entry->x_id = x_id;
        !            75:        new_entry->data = data;
        !            76: 
        !            77:        /* Insert the new entry. */
        !            78:        insque(new_entry, entry->prev);
        !            79: }

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