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-rw-r--r--kernel/timeconst.bc108
1 files changed, 108 insertions, 0 deletions
diff --git a/kernel/timeconst.bc b/kernel/timeconst.bc
new file mode 100644
index 000000000000..511bdf2cafda
--- /dev/null
+++ b/kernel/timeconst.bc
@@ -0,0 +1,108 @@
1scale=0
2
3define 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. */
14define 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) */
20define 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. */
31define 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
41define timeconst(hz) {
42 print "/* Automatically generated by kernel/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 \qkernel/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 print "\n"
102
103 print "#endif /* KERNEL_TIMECONST_H */\n"
104 }
105 halt
106}
107
108timeconst(hz)