blender/source/blender/blenlib/intern/array_utils.c

/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/** \file blender/blenlib/intern/array_utils.c
 *  \ingroup bli
 *  \brief Generic array manipulation API.
 *
 * \warning Some array operations here are inherently inefficient,
 * and only included for the cases where the performance is acceptable.
 * Use with care.
 */
#include <string.h>
#include <stdlib.h>

#include "MEM_guardedalloc.h"

#include "BLI_array_utils.h"

#include "BLI_sys_types.h"
#include "BLI_utildefines.h"
#include "BLI_alloca.h"

#include "BLI_strict_flags.h"

/**
 *In-place array reverse.
 *
 * Access via #BLI_array_reverse
 */
void _bli_array_reverse(void *arr_v, unsigned int arr_len, size_t arr_stride)
{
	const unsigned int arr_stride_uint = (unsigned int)arr_stride;
	const unsigned int arr_half_stride = (arr_len / 2) * arr_stride_uint;
	unsigned int i, i_end;
	char *arr = arr_v;
	char *buf = BLI_array_alloca(buf, arr_stride);

	for (i = 0, i_end = (arr_len - 1) * arr_stride_uint;
	     i < arr_half_stride;
	     i += arr_stride_uint, i_end -= arr_stride_uint)
	{
		memcpy(buf, &arr[i], arr_stride);
		memcpy(&arr[i], &arr[i_end], arr_stride);
		memcpy(&arr[i_end], buf, arr_stride);
	}
}

/**
 * In-place array wrap.
 * (rotate the array one step forward or backwards).
 *
 * Access via #BLI_array_wrap
 */
void _bli_array_wrap(void *arr_v, unsigned int arr_len, size_t arr_stride, int dir)
{
	char *arr = arr_v;
	char *buf = BLI_array_alloca(buf, arr_stride);

	if (dir == -1) {
		memcpy(buf, arr, arr_stride);
		memmove(arr, arr + arr_stride, arr_stride * (arr_len - 1));
		memcpy(arr + (arr_stride * (arr_len - 1)), buf, arr_stride);
	}
	else if (dir == 1) {
		memcpy(buf, arr + (arr_stride * (arr_len - 1)), arr_stride);
		memmove(arr + arr_stride, arr, arr_stride * (arr_len - 1));
		memcpy(arr, buf, arr_stride);
	}
	else {
		BLI_assert(0);
	}
}

/**
 *In-place array permute.
 * (re-arrange elements based on an array of indices).
 *
 * Access via #BLI_array_wrap
 */
void _bli_array_permute(
        void *arr_v, const unsigned int arr_len, const size_t arr_stride,
        const unsigned int *order, void *arr_temp)
{
	const size_t len = arr_len * arr_stride;
	const unsigned int arr_stride_uint = (unsigned int)arr_stride;
	void *arr_orig;
	unsigned int i;

	if (arr_temp == NULL) {
		arr_orig = MEM_mallocN(len, __func__);
	}
	else {
		arr_orig = arr_temp;
	}

	memcpy(arr_orig, arr_v, len);

	for (i = 0; i < arr_len; i++) {
		BLI_assert(order[i] < arr_len);
		memcpy(POINTER_OFFSET(arr_v,    arr_stride_uint * i),
		       POINTER_OFFSET(arr_orig, arr_stride_uint * order[i]),
		       arr_stride);
	}

	if (arr_temp == NULL) {
		MEM_freeN(arr_orig);
	}
}

/**
 * Find the first index of an item in an array.
 *
 * Access via #BLI_array_findindex
 *
 * \note Not efficient, use for error checks/asserts.
 */
int _bli_array_findindex(const void *arr, unsigned int arr_len, size_t arr_stride, const void *p)
{
	const char *arr_step = (const char *)arr;
	unsigned int i;
	for (i = 0; i < arr_len; i++, arr_step += arr_stride) {
		if (memcmp(arr_step, p, arr_stride) == 0) {
			return (int)i;
		}
	}
	return -1;
}

void _bli_array_binary_and(
        void *arr, const void *arr_a, const void *arr_b,
        unsigned int arr_len, size_t arr_stride)
{
	char *dst   = arr;
	const char *src_a = arr_a;
	const char *src_b = arr_b;

	size_t i = arr_stride * arr_len;
	while (i--) {
		*(dst++) = *(src_a++) & *(src_b++);
	}
}

void _bli_array_binary_or(
        void *arr, const void *arr_a, const void *arr_b,
        unsigned int arr_len, size_t arr_stride)
{
	char *dst   = arr;
	const char *src_a = arr_a;
	const char *src_b = arr_b;

	size_t i = arr_stride * arr_len;
	while (i--) {
		*(dst++) = *(src_a++) | *(src_b++);
	}
}

/**
 * Utility function to iterate over contiguous items in an array.
 *
 * \param use_wrap: Detect contiguous ranges across the first/last points.
 * In this case the second index of \a span_step may be lower than the first,
 * which indicates the values are wrapped.
 * \param use_delimit_bounds: When false, ranges that defined by the start/end indices are excluded.
 * This option has no effect when \a use_wrap is enabled.
 * \param test_fn: Function to test if the item should be included in the range.
 * \param user_data: User data for \a test_fn.
 * \param span_step: Indices to iterate over,
 * initialize both values to the array length to initialize iteration.
 * \param: r_span_len: The length of the span, useful when \a use_wrap is enabled,
 * where calculating the length isnt a simple subtraction.
 */
bool _bli_array_iter_span(
        const void *arr,
        unsigned int arr_len, size_t arr_stride,
        bool use_wrap, bool use_delimit_bounds,
        bool (*test_fn)(const void *arr_item, void *user_data), void *user_data,
        unsigned int span_step[2], unsigned int *r_span_len)
{
	if (arr_len == 0) {
		return false;
	}
	else if (use_wrap && (span_step[0] != arr_len) && (span_step[0] > span_step[1])) {
		return false;
	}

	const unsigned int arr_stride_uint = (unsigned int)arr_stride;
	const void *item_prev;
	bool test_prev;

	unsigned int i_curr;

	if ((span_step[0] == arr_len) && (span_step[1] == arr_len)) {
		if (use_wrap) {
			item_prev = POINTER_OFFSET(arr, (arr_len - 1) * arr_stride_uint);
			i_curr = 0;
			test_prev = test_fn(item_prev, user_data);
		}
		else if (use_delimit_bounds == false) {
			item_prev = arr;
			i_curr = 1;
			test_prev = test_fn(item_prev, user_data);
		}
		else {
			item_prev = NULL;
			i_curr = 0;
			test_prev = false;
		}
	}
	else if ((i_curr = span_step[1] + 2) < arr_len) {
		item_prev = POINTER_OFFSET(arr, (span_step[1] + 1) * arr_stride_uint);
		test_prev = test_fn(item_prev, user_data);
	}
	else {
		return false;
	}
	BLI_assert(i_curr < arr_len);

	const void *item_curr = POINTER_OFFSET(arr, i_curr * arr_stride_uint);

	while (i_curr < arr_len) {
		bool test_curr = test_fn(item_curr, user_data);
		if ((test_prev == false) &&
		    (test_curr == true))
		{
			unsigned int span_len;
			unsigned int i_step_prev = i_curr;

			if (use_wrap) {
				unsigned int i_step = i_curr + 1;
				if (UNLIKELY(i_step == arr_len)) {
					i_step = 0;
				}
				while (test_fn(POINTER_OFFSET(arr, i_step * arr_stride_uint), user_data)) {
					i_step_prev = i_step;
					i_step++;
					if (UNLIKELY(i_step == arr_len)) {
						i_step = 0;
					}
				}

				if (i_step_prev < i_curr) {
					span_len = (i_step_prev + (arr_len - i_curr)) + 1;
				}
				else {
					span_len = (i_step_prev - i_curr) + 1;
				}
			}
			else {
				unsigned int i_step = i_curr + 1;
				while ((i_step != arr_len) &&
				       test_fn(POINTER_OFFSET(arr, i_step * arr_stride_uint), user_data))
				{
					i_step_prev = i_step;
					i_step++;
				}

				span_len = (i_step_prev - i_curr) + 1;

				if ((use_delimit_bounds == false) && (i_step_prev == arr_len - 1)) {
					return false;
				}
			}

			span_step[0] = i_curr;
			span_step[1] = i_step_prev;
			*r_span_len  = span_len;

			return true;
		}

		test_prev = test_curr;

		item_prev = item_curr;
		item_curr = POINTER_OFFSET(item_curr, arr_stride_uint);
		i_curr++;
	}

	return false;
}