Function insert_newwords

src/backend/access/bitmap/bitmapinsert.c:505–608

* insert_newwords() -- insert a buffer of new words into a given buffer of * words at a specified position. * * The new words will be inserted into the positions starting from * 'insertPos'(>=0). The original words from 'insertPos' will be shifted * to the right. If the given array does not have enough space to * hold all words, the last '(*numWordsP+numNewWords-maxNumWords)' words * will

 * This function assumes that the number of new words is not greater than BM_HRL_WORD_SIZE.
 */
static void
insert_newwords(BMTIDBuffer* words, uint32 insertPos,
				BMTIDBuffer* new_words, BMTIDBuffer* words_left)
{
	int32	wordNo;
	uint16  bitLoc;

	Assert(new_words->curword <= BM_HRL_WORD_SIZE);
	Assert(insertPos <= words->num_cwords);

	words_left->curword = 0;

	/* if there are no words in the original buffer, we simply copy the new words. */
	if (words->curword == 0)
	{
		memcpy(words->cwords, new_words->cwords, new_words->curword*sizeof(BM_HRL_WORD));
		memcpy(words->hwords, new_words->hwords,
			   BM_CALC_H_WORDS(new_words->curword) * sizeof(BM_HRL_WORD));
		words->curword = new_words->curword;

		return;
	}

	/*
	 * if insertPos is pointing to the position after the maximum position
	 * in this word, we simply copy the new words to leftContentWords.
	 */
	if (insertPos == words->num_cwords)
	{
		memcpy(words_left->cwords, new_words->cwords,
			   new_words->curword * sizeof(BM_HRL_WORD));
		memcpy(words_left->hwords, new_words->hwords,
			   BM_CALC_H_WORDS(new_words->curword) * sizeof(BM_HRL_WORD));
		words_left->curword = new_words->curword;

		return;
	}

	Assert(words->curword > 0);

	/* Calculate how many words left after this insert. */
	if (words->curword + new_words->curword > words->num_cwords)
		words_left->curword = words->curword + new_words->curword - words->num_cwords;
	MemSet(words_left->hwords, 0, BM_NUM_OF_HEADER_WORDS * sizeof(BM_HRL_WORD));

	/*
	 * Walk from the last word in the array back to 'insertPos'.
	 * If the word no + new_words->curword is greater than words->num_cwords,
	 * we store these words in words_left.
	 */
	for (wordNo=words->curword-1; wordNo>=0 && wordNo>=insertPos; wordNo--)
	{
		if (wordNo + new_words->curword >= words->num_cwords)
		{
			words_left->cwords[wordNo+new_words->curword-words->num_cwords] = 
				words->cwords[wordNo];
			if (IS_FILL_WORD(words->hwords, wordNo))
			{