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| author | Joe Ludwig <[email protected]> | 2013-06-26 15:22:04 -0700 |
|---|---|---|
| committer | Joe Ludwig <[email protected]> | 2013-06-26 15:22:04 -0700 |
| commit | 39ed87570bdb2f86969d4be821c94b722dc71179 (patch) | |
| tree | abc53757f75f40c80278e87650ea92808274aa59 /mp/src/tier1/qsort_s.cpp | |
| download | source-sdk-2013-39ed87570bdb2f86969d4be821c94b722dc71179.tar.xz source-sdk-2013-39ed87570bdb2f86969d4be821c94b722dc71179.zip | |
First version of the SOurce SDK 2013
Diffstat (limited to 'mp/src/tier1/qsort_s.cpp')
| -rw-r--r-- | mp/src/tier1/qsort_s.cpp | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/mp/src/tier1/qsort_s.cpp b/mp/src/tier1/qsort_s.cpp new file mode 100644 index 00000000..6c5b2a95 --- /dev/null +++ b/mp/src/tier1/qsort_s.cpp @@ -0,0 +1,112 @@ +//========= Copyright Valve Corporation, All rights reserved. ============//
+/******************************************************************/
+/* qsort.c -- Non-Recursive ANSI Quicksort function */
+/* */
+/* Public domain by Raymond Gardner, Englewood CO February 1991 */
+/* */
+/* Usage: */
+/* qsort(base, nbr_elements, width_bytes, compare_function); */
+/* void *base; */
+/* size_t nbr_elements, width_bytes; */
+/* int (*compare_function)(const void *, const void *); */
+/* */
+/* Sorts an array starting at base, of length nbr_elements, each */
+/* element of size width_bytes, ordered via compare_function, */
+/* which is called as (*compare_function)(ptr_to_element1, */
+/* ptr_to_element2) and returns < 0 if element1 < element2, */
+/* 0 if element1 = element2, > 0 if element1 > element2. */
+/* Most refinements are due to R. Sedgewick. See "Implementing */
+/* Quicksort Programs", Comm. ACM, Oct. 1978, and Corrigendum, */
+/* Comm. ACM, June 1979. */
+/******************************************************************/
+
+// modified to take (and use) a context object, ala Microsoft's qsort_s
+// "extension" to the stdlib
+
+#include <stddef.h> /* for size_t definition */
+
+/*
+** swap nbytes between a and b
+*/
+
+static void swap_bytes(char *a, char *b, size_t nbytes)
+{
+ char tmp;
+ do {
+ tmp = *a; *a++ = *b; *b++ = tmp;
+ } while ( --nbytes );
+}
+
+#define SWAP(a, b) (swap_bytes((char *)(a), (char *)(b), size))
+
+#define COMP(ctx, a, b) ((*comp)((void *)ctx, (void *)(a), (void *)(b)))
+
+#define T 7 /* subfiles of T or fewer elements will */
+ /* be sorted by a simple insertion sort */
+ /* Note! T must be at least 3 */
+
+extern "C" void qsort_s(void *basep, size_t nelems, size_t size,
+ int (*comp)(void *, const void *, const void *),
+ void *ctx)
+{
+ char *stack[40], **sp; /* stack and stack pointer */
+ char *i, *j, *limit; /* scan and limit pointers */
+ size_t thresh; /* size of T elements in bytes */
+ char *base; /* base pointer as char * */
+
+ base = (char *)basep; /* set up char * base pointer */
+ thresh = T * size; /* init threshold */
+ sp = stack; /* init stack pointer */
+ limit = base + nelems * size;/* pointer past end of array */
+ for ( ;; ) { /* repeat until break... */
+ if ( limit - base > thresh ) { /* if more than T elements */
+ /* swap base with middle */
+ SWAP((((limit-base)/size)/2)*size+base, base);
+ i = base + size; /* i scans left to right */
+ j = limit - size; /* j scans right to left */
+ if ( COMP(ctx, i, j) > 0 ) /* Sedgewick's */
+ SWAP(i, j); /* three-element sort */
+ if ( COMP(ctx, base, j) > 0 )/* sets things up */
+ SWAP(base, j); /* so that */
+ if ( COMP(ctx, i, base) > 0 )/* *i <= *base <= *j */
+ SWAP(i, base); /* *base is pivot element */
+ for ( ;; ) { /* loop until break */
+ do /* move i right */
+ i += size; /* until *i >= pivot */
+ while ( COMP(ctx, i, base) < 0 );
+ do /* move j left */
+ j -= size; /* until *j <= pivot */
+ while ( COMP(ctx, j, base) > 0 );
+ if ( i > j ) /* if pointers crossed */
+ break; /* break loop */
+ SWAP(i, j); /* else swap elements, keep scanning*/
+ }
+ SWAP(base, j); /* move pivot into correct place */
+ if ( j - base > limit - i ) { /* if left subfile larger */
+ sp[0] = base; /* stack left subfile base */
+ sp[1] = j; /* and limit */
+ base = i; /* sort the right subfile */
+ } else { /* else right subfile larger*/
+ sp[0] = i; /* stack right subfile base */
+ sp[1] = limit; /* and limit */
+ limit = j; /* sort the left subfile */
+ }
+ sp += 2; /* increment stack pointer */
+ } else { /* else subfile is small, use insertion sort */
+ for ( j = base, i = j+size; i < limit; j = i, i += size )
+ for ( ; COMP(ctx, j, j+size) > 0; j -= size ) {
+ SWAP(j, j+size);
+ if ( j == base )
+ break;
+ }
+ if ( sp != stack ) { /* if any entries on stack */
+ sp -= 2; /* pop the base and limit */
+ base = sp[0];
+ limit = sp[1];
+ } else /* else stack empty, done */
+ break;
+ }
+ }
+}
+
+
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