forked from len0rd/rockbox
09aa8de52c
This brings the puzzles source in sync with Simon's branch, commit fd304c5 (from March 2024), with some added Rockbox-specific compatibility changes: https://www.franklinwei.com/git/puzzles/commit/?h=rockbox-devel&id=516830d9d76bdfe64fe5ccf2a9b59c33f5c7c078 There are quite a lot of backend changes, including a new "Mosaic" puzzle. In addition, some new frontend changes were necessary: - New "Preferences" menu to access the user preferences system. - Enabled spacebar input for several games. Change-Id: I94c7df674089c92f32d5f07025f6a1059068af1e
71 lines
1.9 KiB
C
71 lines
1.9 KiB
C
/*
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* Implement arraysort() defined in puzzles.h.
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*
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* Strategy: heapsort.
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*/
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#include <stddef.h>
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#include <string.h>
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#include "puzzles.h"
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#define PTR(i) ((char *)array + size * (i))
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#define SWAP(i,j) swap_regions(PTR(i), PTR(j), size)
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#define CMP(i,j) cmp(PTR(i), PTR(j), ctx)
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#define LCHILD(i) (2*(i)+1)
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#define RCHILD(i) (2*(i)+2)
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#define PARENT(i) (((i)-1)/2)
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static void downheap(void *array, size_t nmemb, size_t size,
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arraysort_cmpfn_t cmp, void *ctx, size_t i)
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{
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while (LCHILD(i) < nmemb) {
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/* Identify the smallest element out of i and its children. */
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size_t j = i;
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if (CMP(j, LCHILD(i)) < 0)
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j = LCHILD(i);
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if (RCHILD(i) < nmemb &&
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CMP(j, RCHILD(i)) < 0)
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j = RCHILD(i);
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if (j == i)
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return; /* smallest element is already where it should be */
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SWAP(j, i);
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i = j;
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}
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}
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void arraysort_fn(void *array, size_t nmemb, size_t size,
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arraysort_cmpfn_t cmp, void *ctx)
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{
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size_t i;
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if (nmemb < 2)
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return; /* trivial */
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/*
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* Stage 1: build the heap.
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*
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* Linear-time if we do it by downheaping the elements in
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* decreasing order of index, instead of the more obvious approach
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* of upheaping in increasing order. (Also, it means we don't need
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* the upheap function at all.)
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*
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* We don't need to downheap anything in the second half of the
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* array, because it can't have any children to swap with anyway.
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*/
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for (i = PARENT(nmemb-1) + 1; i-- > 0 ;)
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downheap(array, nmemb, size, cmp, ctx, i);
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/*
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* Stage 2: dismantle the heap by repeatedly swapping the root
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* element (at index 0) into the last position and then
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* downheaping the new root.
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*/
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for (i = nmemb-1; i > 0; i--) {
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SWAP(0, i);
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downheap(array, i, size, cmp, ctx, 0);
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}
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}
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