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)