testcases/stalls.c

   1 #define NCAND 64
   2
   3 #ifdef STANDALONE
   4 asm("        .globl _start");
   5 asm("        # This is to stay compatible with crt0 C programs (starts at 0x80000003c)");
   6 asm("_init:");
   7 asm("        nop                     # 0x80000000");
   8 asm("        nop");
   9 asm("        nop");
  10 asm("        nop");
  11 asm("        nop");
  12 asm("        nop");
  13 asm("        nop");
  14 asm("        nop");
  15 asm("        nop");
  16 asm("        nop");
  17 asm("        nop");
  18 asm("        nop");
  19 asm("        nop");
  20 asm("        nop");
  21 asm("        nop");
  22 asm("");
  23 asm("# 0x8000003c");
  24 asm("_start: lui   $29,0x8000    ");
  25 asm("        ori   $29,$29,0x2000"); /* + 8KiB */
  26 asm("        jal   main          ");
  27 asm("        nop                 ");
  28 asm("        break               ");
  29 #endif
  30
  31 static inline putchar(unsigned ch)
  32 {
  33   if (ch == '\n')
  34     putchar('\r');
  35
  36 #define SER_OUTBUSY() (*(volatile unsigned *)0xFF000000 != 0)
  37 #define SER_OUT(data) (*(volatile unsigned *)0xFF000000 = (data))
  38   while (SER_OUTBUSY())
  39     ;
  40   SER_OUT(ch);
  41 }
  42
  43
  44 static void put_unsigned(unsigned n)
  45 {
  46   // (unsigned)-1 == 4294967295
  47   static unsigned powers10[] = {
  48     1000000000,
  49     100000000,
  50     10000000,
  51     1000000,
  52     100000,
  53     10000,
  54     1000,
  55     100,
  56     10,
  57     1,
  58     0
  59   };
  60   unsigned *p;
  61   unsigned leading_zero = 1;
  62
  63   if (!n) {
  64     putchar('0');
  65     return;
  66   }
  67
  68   for (p = powers10; *p; ++p) {
  69     unsigned scale = *p;
  70     unsigned i, t;
  71
  72     for (i = 0; n >= scale; ++i, n -= scale)
  73       ;
  74     if (i != 0 || !leading_zero) {
  75       putchar('0' + i);
  76       leading_zero = 0;
  77     }
  78   }
  79 }
  80
  81 main()
  82 {
  83   // 0 1 2 3  4  5  6
  84   // 3 5 7 9 11 13 15
  85   static unsigned cand[NCAND];
  86
  87   unsigned i, j, n = 0;
  88   unsigned *p;
  89
  90   for (i = 0; i != NCAND*32; ++i) {
  91     if ((cand[i >> 5] & (1 << (i & 31))) == 0) {
  92       unsigned p = 2*i+3;
  93       put_unsigned(p);
  94       putchar(' ');
  95       // Remove 3p 5p 7p 9p ...
  96       // 3p ~ cand[(3p - 3)/2] = cand[(6i+9-3)/2] = cand[3i+3]
  97       // 5p ~ cand[(5p - 3)/2] = cand[(10i+15-3)/2] = cand[5i+6]
  98       // ...
  99       // np ~ cand[(np - 3)/2] = cand[(2ni+3n-3)/2] = cand[ni+1.5(n-1)]
 100       //                       = cand[pos(np)]
 101       //
 102       // (n+2)p ~ cand[((n+2)p - 3)/2] =
 103       //          cand[((np + 2p) - 3) / 2] =
 104       //          cand[(np - 3)/2 + p]
 105       //
 106       for (j = i + p; j < NCAND*32; j += p) {
 107         cand[j >> 5] |= 1 << (j & 31);
 108         // printf("-%d ", 2*j+3);
 109       }
 110       if (++n == 15) {
 111         putchar('\n');
 112         n = 0;
 113       }
 114     }
 115   }
 116   putchar('\n');
 117 }