kernel/time/timeconst.bc

   1 scale=0
   2
   3 define gcd(a,b) {
   4         auto t;
   5         while (b) {
   6                 t = b;
   7                 b = a % b;
   8                 a = t;
   9         }
  10         return a;
  11 }
  12
  13 /* Division by reciprocal multiplication. */
  14 define fmul(b,n,d) {
  15        return (2^b*n+d-1)/d;
  16 }
  17
  18 /* Adjustment factor when a ceiling value is used.  Use as:
  19    (imul * n) + (fmulxx * n + fadjxx) >> xx) */
  20 define fadj(b,n,d) {
  21         auto v;
  22         d = d/gcd(n,d);
  23         v = 2^b*(d-1)/d;
  24         return v;
  25 }
  26
  27 /* Compute the appropriate mul/adj values as well as a shift count,
  28    which brings the mul value into the range 2^b-1 <= x < 2^b.  Such
  29    a shift value will be correct in the signed integer range and off
  30    by at most one in the upper half of the unsigned range. */
  31 define fmuls(b,n,d) {
  32         auto s, m;
  33         for (s = 0; 1; s++) {
  34                 m = fmul(s,n,d);
  35                 if (m >= 2^(b-1))
  36                         return s;
  37         }
  38         return 0;
  39 }
  40
  41 define timeconst(hz) {
  42         print "/* Automatically generated by kernel/time/timeconst.bc */\n"
  43         print "/* Time conversion constants for HZ == ", hz, " */\n"
  44         print "\n"
  45
  46         print "#ifndef KERNEL_TIMECONST_H\n"
  47         print "#define KERNEL_TIMECONST_H\n\n"
  48
  49         print "#include <linux/param.h>\n"
  50         print "#include <linux/types.h>\n\n"
  51
  52         print "#if HZ != ", hz, "\n"
  53         print "#error \qinclude/generated/timeconst.h has the wrong HZ value!\q\n"
  54         print "#endif\n\n"
  55
  56         if (hz < 2) {
  57                 print "#error Totally bogus HZ value!\n"
  58         } else {
  59                 s=fmuls(32,1000,hz)
  60                 obase=16
  61                 print "#define HZ_TO_MSEC_MUL32\tU64_C(0x", fmul(s,1000,hz), ")\n"
  62                 print "#define HZ_TO_MSEC_ADJ32\tU64_C(0x", fadj(s,1000,hz), ")\n"
  63                 obase=10
  64                 print "#define HZ_TO_MSEC_SHR32\t", s, "\n"
  65
  66                 s=fmuls(32,hz,1000)
  67                 obase=16
  68                 print "#define MSEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000), ")\n"
  69                 print "#define MSEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000), ")\n"
  70                 obase=10
  71                 print "#define MSEC_TO_HZ_SHR32\t", s, "\n"
  72
  73                 obase=10
  74                 cd=gcd(hz,1000)
  75                 print "#define HZ_TO_MSEC_NUM\t\t", 1000/cd, "\n"
  76                 print "#define HZ_TO_MSEC_DEN\t\t", hz/cd, "\n"
  77                 print "#define MSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
  78                 print "#define MSEC_TO_HZ_DEN\t\t", 1000/cd, "\n"
  79                 print "\n"
  80
  81                 s=fmuls(32,1000000,hz)
  82                 obase=16
  83                 print "#define HZ_TO_USEC_MUL32\tU64_C(0x", fmul(s,1000000,hz), ")\n"
  84                 print "#define HZ_TO_USEC_ADJ32\tU64_C(0x", fadj(s,1000000,hz), ")\n"
  85                 obase=10
  86                 print "#define HZ_TO_USEC_SHR32\t", s, "\n"
  87
  88                 s=fmuls(32,hz,1000000)
  89                 obase=16
  90                 print "#define USEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000000), ")\n"
  91                 print "#define USEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000000), ")\n"
  92                 obase=10
  93                 print "#define USEC_TO_HZ_SHR32\t", s, "\n"
  94
  95                 obase=10
  96                 cd=gcd(hz,1000000)
  97                 print "#define HZ_TO_USEC_NUM\t\t", 1000000/cd, "\n"
  98                 print "#define HZ_TO_USEC_DEN\t\t", hz/cd, "\n"
  99                 print "#define USEC_TO_HZ_NUM\t\t", hz/cd, "\n"
 100                 print "#define USEC_TO_HZ_DEN\t\t", 1000000/cd, "\n"
 101
 102                 cd=gcd(hz,1000000000)
 103                 print "#define HZ_TO_NSEC_NUM\t\t", 1000000000/cd, "\n"
 104                 print "#define HZ_TO_NSEC_DEN\t\t", hz/cd, "\n"
 105                 print "#define NSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
 106                 print "#define NSEC_TO_HZ_DEN\t\t", 1000000000/cd, "\n"
 107                 print "\n"
 108
 109                 print "#endif /* KERNEL_TIMECONST_H */\n"
 110         }
 111         halt
 112 }
 113
 114 hz = read();
 115 timeconst(hz)