Return to alloc.c CVS log

Up to [OS/2 SDKs] / os2sdk / demos / examples / alloc

Annotation of os2sdk/demos/examples/alloc/alloc.c, revision 1.1.1.1

1.1       root        1: /*
                      2:  * Example of DOSALLOCSEG/DOSFREESEG usage.
                      3:  *
                      4:  * Shows how to allocate a segment, create a
                      5:  * pointer to it, access the segment, and free it.
                      6:  * Creates one 16K segment by default, or the number
                      7:  * specified on the command line. After all are allocated,
                      8:  * writes a 0 into the first byte of each. If you run this on
                      9:  * a system with swapping enabled you can allocate more segments
                     10:  * segments than fit in physcical memory, and exercise your disk.
                     11:  *
                     12:  * This program works Family API mode, although obviously
                     13:  * without the benefit of virtual memory & swapping.
                     14:  *
                     15:  * Compile as:  cl -AL -G2 -Lp alloc.c
                     16:  *
                     17:  * Copyright (C) Microsoft Corp. 1986
                     18:  */
                     19: 
                     20: #include <doscalls.h>
                     21: #include <malloc.h>
                     22: #include <dos.h>
                     23: 
                     24: #define SEGSIZE        (16 * 1024)     /* size of each segment allocated */
                     25: #define NOTSHARED 0
                     26: 
                     27: main(argc, argv)
                     28: int argc;
                     29: char *argv[];
                     30: {
                     31:        unsigned *seglist;      /* pointer to list of segments */
                     32:        char *p;                /* pointer used to access segments */
                     33:        register int i, j;
                     34:        int rc;                 /* system call return code */
                     35: 
                     36:        if(argc == 2)                   /* number of segments to allocate */
                     37:                i = atoi(argv[1]);
                     38:        else
                     39:                i = 1;
                     40: 
                     41:        seglist = (unsigned *)malloc(2 * i);    /* list of segment selectors */
                     42: 
                     43:        /* allocate segment(s) */
                     44:        for(j = 0; j < i; j++) {
                     45:                rc = DOSALLOCSEG(SEGSIZE, &seglist[j], NOTSHARED);
                     46:                if(rc == 0)
                     47:                        printf("allocated segment %d\n", j);
                     48:                else {
                     49:                        printf("allocation failed on segment %d\n", j);
                     50:                        i = j;
                     51:                }
                     52:        }
                     53: 
                     54:        /* write 0 into first byte of each segment */
                     55:        for(j = 0; j < i; j++) {
                     56:                FP_SEG(p) = seglist[j];         /* make long pointer to seg */
                     57:                FP_OFF(p) = 0;
                     58:                printf("touching segment %d\n", j);
                     59:                p[0] = 0;                       /* put zero in first byte */
                     60:        }
                     61: 
                     62:        /* free each segment */
                     63:        for(j = 0; j < i; j++) {
                     64:                printf("freeing segment %d\n", j);
                     65:                DOSFREESEG(seglist[j]);
                     66:        }
                     67: }

This archive runs on limited infrastructure. Preserving old code on modern bandwidth. Automated agents are requested to crawl responsibly.