PDP33_generator

#include <stdbool.h>
#include <stdio.h>
#include <stdint.h>
#include <time.h>
#include <stdlib.h>
#include <errno.h>

#define LIMIT (999999999)

#ifndef N
  #define N 50000L
#endif

static uint16_t highest_bit(uint64_t v) {
    uint16_t out = 0;
    while (v > 0) {
        v >>= 1;
        ++out;
    }
    return out;
}

uint32_t myrand() {
    static bool init = 0;
    static uint16_t n;
    static uint16_t shift;
    if (!init) {
        uint16_t randbits = highest_bit(RAND_MAX + (uint64_t)1L);
        uint16_t outbits = highest_bit(LIMIT);
        n = (outbits + randbits - 1)/randbits;
        shift = randbits;
        init = 1;
    }
    uint32_t out = 0;
    for (uint16_t i=0; i<n; ++i) {
        out |= rand() << (i*shift);
    }
    return out % LIMIT;
}

int main(int argc, char *argv[])
{
register long i, prev, code=1, cnt;
int money, choose;
char tr;

FILE *fp;

    if (argc < 2)
    {
        fp=fopen("testfile.txt","w+");
        if (!fp)
        {
            perror("Opening output file...");
            exit(1);
        }
    }
    else
    {
        fp=fopen(argv[1],"w+");
        if (!fp)
        {
            perror("Opening output file...");
            exit(1);
        }
    }
    srand(time(NULL));
    fprintf(fp,"%ld\n", 2*N); /* Write something just to occupy first line */
    for (i=0;i<N; i++)
    {
        choose = rand() % 2;
        tr = (choose == 0 ? 'd' : 'w');
        prev=code;
        code=(long)myrand();
        if (code==0) code=1;
        money=rand();
        if (tr=='w')
        {
            fprintf(fp,"%c %ld %d\n", tr, prev, money);
            fprintf(fp,"d %ld %d\n", code, money);
            cnt += 2;
        }
        else
        {
            fprintf(fp,"%c %ld %d\n", tr, code, money);
            cnt++;
        }
        fprintf(fp,"q %ld\n", prev);
        cnt++;
    }
    rewind(fp);
    fprintf(fp, "%ld\n", cnt+1);
    fclose(fp);
    return 0;
}