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 @@
+scale=0
+
+define gcd(a,b) {
+        auto t;
+        while (b) {
+                t = b;
+                b = a % b;
+                a = t;
+        }
+        return a;
+}
+
+/* Division by reciprocal multiplication. */
+define fmul(b,n,d) {
+       return (2^b*n+d-1)/d;
+}
+
+/* Adjustment factor when a ceiling value is used.  Use as:
+   (imul * n) + (fmulxx * n + fadjxx) >> xx) */
+define fadj(b,n,d) {
+        auto v;
+        d = d/gcd(n,d);
+        v = 2^b*(d-1)/d;
+        return v;
+}
+
+/* Compute the appropriate mul/adj values as well as a shift count,
+   which brings the mul value into the range 2^b-1 <= x < 2^b.  Such
+   a shift value will be correct in the signed integer range and off
+   by at most one in the upper half of the unsigned range. */
+define fmuls(b,n,d) {
+        auto s, m;
+        for (s = 0; 1; s++) {
+                m = fmul(s,n,d);
+                if (m >= 2^(b-1))
+                        return s;
+        }
+        return 0;
+}
+
+define timeconst(hz) {
+        print "/* Automatically generated by kernel/timeconst.bc */\n"
+        print "/* Time conversion constants for HZ == ", hz, " */\n"
+        print "\n"
+
+        print "#ifndef KERNEL_TIMECONST_H\n"
+        print "#define KERNEL_TIMECONST_H\n\n"
+
+        print "#include <linux/param.h>\n"
+        print "#include <linux/types.h>\n\n"
+
+        print "#if HZ != ", hz, "\n"
+        print "#error \qkernel/timeconst.h has the wrong HZ value!\q\n"
+        print "#endif\n\n"
+
+        if (hz < 2) {
+                print "#error Totally bogus HZ value!\n"
+        } else {
+                s=fmuls(32,1000,hz)
+                obase=16
+                print "#define HZ_TO_MSEC_MUL32\tU64_C(0x", fmul(s,1000,hz), ")\n"
+                print "#define HZ_TO_MSEC_ADJ32\tU64_C(0x", fadj(s,1000,hz), ")\n"
+                obase=10
+                print "#define HZ_TO_MSEC_SHR32\t", s, "\n"
+
+                s=fmuls(32,hz,1000)
+                obase=16
+                print "#define MSEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000), ")\n"
+                print "#define MSEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000), ")\n"
+                obase=10
+                print "#define MSEC_TO_HZ_SHR32\t", s, "\n"
+
+                obase=10
+                cd=gcd(hz,1000)
+                print "#define HZ_TO_MSEC_NUM\t\t", 1000/cd, "\n"
+                print "#define HZ_TO_MSEC_DEN\t\t", hz/cd, "\n"
+                print "#define MSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
+                print "#define MSEC_TO_HZ_DEN\t\t", 1000/cd, "\n"
+                print "\n"
+
+                s=fmuls(32,1000000,hz)
+                obase=16
+                print "#define HZ_TO_USEC_MUL32\tU64_C(0x", fmul(s,1000000,hz), ")\n"
+                print "#define HZ_TO_USEC_ADJ32\tU64_C(0x", fadj(s,1000000,hz), ")\n"
+                obase=10
+                print "#define HZ_TO_USEC_SHR32\t", s, "\n"
+
+                s=fmuls(32,hz,1000000)
+                obase=16
+                print "#define USEC_TO_HZ_MUL32\tU64_C(0x", fmul(s,hz,1000000), ")\n"
+                print "#define USEC_TO_HZ_ADJ32\tU64_C(0x", fadj(s,hz,1000000), ")\n"
+                obase=10
+                print "#define USEC_TO_HZ_SHR32\t", s, "\n"
+
+                obase=10
+                cd=gcd(hz,1000000)
+                print "#define HZ_TO_USEC_NUM\t\t", 1000000/cd, "\n"
+                print "#define HZ_TO_USEC_DEN\t\t", hz/cd, "\n"
+                print "#define USEC_TO_HZ_NUM\t\t", hz/cd, "\n"
+                print "#define USEC_TO_HZ_DEN\t\t", 1000000/cd, "\n"
+                print "\n"
+
+                print "#endif /* KERNEL_TIMECONST_H */\n"
+        }
+        halt
+}
+
+timeconst(hz)