113 lines
4.4 KiB
C
113 lines
4.4 KiB
C
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/*************************************************************************/
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/* */
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/* SNU-RT Benchmark Suite for Worst Case Timing Analysis */
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/* ===================================================== */
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/* Collected and Modified by S.-S. Lim */
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/* sslim@archi.snu.ac.kr */
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/* Real-Time Research Group */
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/* Seoul National University */
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/* */
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/* */
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/* < Features > - restrictions for our experimental environment */
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/* */
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/* 1. Completely structured. */
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/* - There are no unconditional jumps. */
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/* - There are no exit from loop bodies. */
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/* (There are no 'break' or 'return' in loop bodies) */
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/* 2. No 'switch' statements. */
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/* 3. No 'do..while' statements. */
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/* 4. Expressions are restricted. */
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/* - There are no multiple expressions joined by 'or', */
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/* 'and' operations. */
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/* 5. No library calls. */
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/* - All the functions needed are implemented in the */
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/* source file. */
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/* */
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/* */
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/*************************************************************************/
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/* */
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/* FILE: select.c */
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/* SOURCE : Numerical Recipes in C - The Second Edition */
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/* */
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/* DESCRIPTION : */
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/* */
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/* A function to select the Nth largest number in the floating poi- */
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/* nt array arr[]. */
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/* The parameters to function select are k and n. Then the function */
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/* selects k-th largest number out of n original numbers. */
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/* */
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/* REMARK : */
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/* */
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/* EXECUTION TIME : */
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/* */
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/* */
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/*************************************************************************/
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#define SWAP(a,b) temp=(a);(a)=(b);(b)=temp;
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float arr[20] = {
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5, 4, 10.3, 1.1, 5.7, 100, 231, 111, 49.5, 99,
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10, 150, 222.22, 101, 77, 44, 35, 20.54, 99.99, 888.88
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};
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float select(unsigned long k, unsigned long n)
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{
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unsigned long i,ir,j,l,mid;
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float a,temp;
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int flag, flag2;
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l=1;
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ir=n;
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flag = flag2 = 0;
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while (!flag) {
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if (ir <= l+1) {
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if (ir == l+1)
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if (arr[ir] < arr[l]) {
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SWAP(arr[l],arr[ir])
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}
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flag = 1;
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} else if (!flag) {
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mid=(l+ir) >> 1;
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SWAP(arr[mid],arr[l+1])
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if (arr[l+1] > arr[ir]) {
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SWAP(arr[l+1],arr[ir])
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}
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if (arr[l] > arr[ir]) {
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SWAP(arr[l],arr[ir])
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}
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if (arr[l+1]> arr[l]) {
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SWAP(arr[l+1],arr[l])
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}
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i=l+1;
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j=ir;
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a=arr[l];
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while (!flag2) {
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i++;
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while (arr[i] < a) i++;
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j--;
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while (arr[j] > a) j--;
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if (j < i) flag2 = 1;
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if (!flag2) SWAP(arr[i],arr[j]);
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}
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arr[l]=arr[j];
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arr[j]=a;
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if (j >= k) ir=j-1;
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if (j <= k) l=i;
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}
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}
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return arr[k];
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}
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main()
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{
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select(10, 20);
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}
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