kernel/time/timeconst.bc

   1 /* SPDX-License-Identifier: GPL-2.0 */
   2
   3 scale=0
   4
   5 define gcd(a,b) {
   6         auto t;
   7         while (b) {
   8                 t = b;
   9                 b = a % b;
  10                 a = t;
  11         }
  12         return a;
  13 }
  14
  15 /* Division by reciprocal multiplication. */
  16 define fmul(b,n,d) {
  17        return (2^b*n+d-1)/d;
  18 }
  19
  20 /* Adjustment factor when a ceiling value is used.  Use as:
  21    (imul * n) + (fmulxx * n + fadjxx) >> xx) */
  22 define fadj(b,n,d) {
  23         auto v;
  24         d = d/gcd(n,d);
  25         v = 2^b*(d-1)/d;
  26         return v;
  27 }
  28
  29 /* Compute the appropriate mul/adj values as well as a shift count,
  30    which brings the mul value into the range 2^b-1 <= x < 2^b.  Such
  31    a shift value will be correct in the signed integer range and off
  32    by at most one in the upper half of the unsigned range. */
  33 define fmuls(b,n,d) {
  34         auto s, m;
  35         for (s = 0; 1; s++) {
  36                 m = fmul(s,n,d);
  37                 if (m >= 2^(b-1))
  38                         return s;
  39         }
  40         return 0;
  41 }
  42
  43 define timeconst(hz) {
  44         print "/* Automatically generated by kernel/time/timeconst.bc */\n"
  45         print "/* Time conversion constants for HZ == ", hz, " */\n"
  46         print "\n"
  47
  48         print "#ifndef KERNEL_TIMECONST_H\n"
  49         print "#define KERNEL_TIMECONST_H\n\n"
  50
  51         print "#include <linux/param.h>\n"
  52         print "#include <linux/types.h>\n\n"
  53
  54         print "#if HZ != ", hz, "\n"
  55         print "#error \qinclude/generated/timeconst.h has the wrong HZ value!\q\n"
  56         print "#endif\n\n"
  57
  58         if (hz < 2) {
  59                 print "#error Totally bogus HZ value!\n"
  60         } else {
  61                 s=fmuls(32,1000,hz)
  62                 obase=16
  63                 print "#define HZ_TO_MSEC_MUL32\tU64_C(0x", fmul(s,1000,hz), ")\n"
  64                 print "#define HZ_TO_MSEC_ADJ32\tU64_C(0x", fadj(s,1000,hz), ")\n"
  65                 obase=10
  66                 print "#define HZ_TO_MSEC_SHR32\t", s, "\n"
  67
  68                 s=fmuls(32,hz,1000)
  69                 obase=16
  70                 print "#define MSEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000), ")\n"
  71                 print "#define MSEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000), ")\n"
  72                 obase=10
  73                 print "#define MSEC_TO_HZ_SHR32\t", s, "\n"
  74
  75                 obase=10
  76                 cd=gcd(hz,1000)
  77                 print "#define HZ_TO_MSEC_NUM\t\t", 1000/cd, "\n"
  78                 print "#define HZ_TO_MSEC_DEN\t\t", hz/cd, "\n"
  79                 print "#define MSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
  80                 print "#define MSEC_TO_HZ_DEN\t\t", 1000/cd, "\n"
  81                 print "\n"
  82
  83                 s=fmuls(32,1000000,hz)
  84                 obase=16
  85                 print "#define HZ_TO_USEC_MUL32\tU64_C(0x", fmul(s,1000000,hz), ")\n"
  86                 print "#define HZ_TO_USEC_ADJ32\tU64_C(0x", fadj(s,1000000,hz), ")\n"
  87                 obase=10
  88                 print "#define HZ_TO_USEC_SHR32\t", s, "\n"
  89
  90                 s=fmuls(32,hz,1000000)
  91                 obase=16
  92                 print "#define USEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000000), ")\n"
  93                 print "#define USEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000000), ")\n"
  94                 obase=10
  95                 print "#define USEC_TO_HZ_SHR32\t", s, "\n"
  96
  97                 obase=10
  98                 cd=gcd(hz,1000000)
  99                 print "#define HZ_TO_USEC_NUM\t\t", 1000000/cd, "\n"
 100                 print "#define HZ_TO_USEC_DEN\t\t", hz/cd, "\n"
 101                 print "#define USEC_TO_HZ_NUM\t\t", hz/cd, "\n"
 102                 print "#define USEC_TO_HZ_DEN\t\t", 1000000/cd, "\n"
 103
 104                 cd=gcd(hz,1000000000)
 105                 print "#define HZ_TO_NSEC_NUM\t\t", 1000000000/cd, "\n"
 106                 print "#define HZ_TO_NSEC_DEN\t\t", hz/cd, "\n"
 107                 print "#define NSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
 108                 print "#define NSEC_TO_HZ_DEN\t\t", 1000000000/cd, "\n"
 109                 print "\n"
 110
 111                 print "#endif /* KERNEL_TIMECONST_H */\n"
 112         }
 113         halt
 114 }
 115
 116 hz = read();
 117 timeconst(hz)