[PATCH v2] replace timeconst bc script with an sh script

[PATCH v2] replace timeconst bc script with an sh script

[Ethan Sommer]

removes the bc build dependency introduced when timeconst.pl was
replaced by timeconst.bc:
70730bca1331 ("kernel: Replace timeconst.pl with a bc script")

Signed-off-by: Ethan Sommer <e5ten.arch@gmail.com>
---
 Documentation/process/changes.rst |   6 --
 Kbuild                            |   4 +-
 kernel/time/timeconst.bc          | 117 -----------------------------
 kernel/time/timeconst.sh          | 118 ++++++++++++++++++++++++++++++
 4 files changed, 120 insertions(+), 125 deletions(-)
 delete mode 100644 kernel/time/timeconst.bc
 create mode 100755 kernel/time/timeconst.sh

diff --git a/Documentation/process/changes.rst b/Documentation/process/changes.rst
index 18735dc460a0..14347f6752ea 100644
--- a/Documentation/process/changes.rst
+++ b/Documentation/process/changes.rst
@@ -108,12 +108,6 @@ Perl
 You will need perl 5 and the following modules: ``Getopt::Long``,
 ``Getopt::Std``, ``File::Basename``, and ``File::Find`` to build the kernel.
 
-BC
---
-
-You will need bc to build kernels 3.10 and higher
-
-
 OpenSSL
 -------
 
diff --git a/Kbuild b/Kbuild
index 8637fd14135f..2b5f2957cf04 100644
--- a/Kbuild
+++ b/Kbuild
@@ -20,9 +20,9 @@ timeconst-file := include/generated/timeconst.h
 
 targets += $(timeconst-file)
 
-filechk_gentimeconst = echo $(CONFIG_HZ) | bc -q $<
+filechk_gentimeconst = $(CONFIG_SHELL) $< $(CONFIG_HZ)
 
-$(timeconst-file): kernel/time/timeconst.bc FORCE
+$(timeconst-file): kernel/time/timeconst.sh FORCE
 	$(call filechk,gentimeconst)
 
 #####
diff --git a/kernel/time/timeconst.bc b/kernel/time/timeconst.bc
deleted file mode 100644
index 7ed0e0fb5831..000000000000
--- a/kernel/time/timeconst.bc
+++ /dev/null
@@ -1,117 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-
-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/time/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 \qinclude/generated/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"
-
-		cd=gcd(hz,1000000000)
-		print "#define HZ_TO_NSEC_NUM\t\t", 1000000000/cd, "\n"
-		print "#define HZ_TO_NSEC_DEN\t\t", hz/cd, "\n"
-		print "#define NSEC_TO_HZ_NUM\t\t", hz/cd, "\n"
-		print "#define NSEC_TO_HZ_DEN\t\t", 1000000000/cd, "\n"
-		print "\n"
-
-		print "#endif /* KERNEL_TIMECONST_H */\n"
-	}
-	halt
-}
-
-hz = read();
-timeconst(hz)
diff --git a/kernel/time/timeconst.sh b/kernel/time/timeconst.sh
new file mode 100755
index 000000000000..20dd24815ae1
--- /dev/null
+++ b/kernel/time/timeconst.sh
@@ -0,0 +1,118 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+
+if [ -z "$1" ]; then
+	printf '%s <HZ>\n' "$0"
+	exit 1
+else
+	hz="$1"
+fi
+
+# 2 to the power of n
+pot() {
+	local i=1
+    local j=1
+	while [ "${j}" -le "$1" ]; do
+		i="$((i * 2))"
+        j="$((j + 1))"
+	done
+	printf '%s\n' "${i}"
+}
+
+# Greatest common denominator
+gcd() {
+	local i="$1"
+	local j="$2"
+	local k
+	while [ "${j}" -ne 0 ]; do
+		k="${j}"
+		j="$((i % j))"
+		i="${k}"
+	done
+	printf '%s\n' "${i}"
+}
+
+# Division by reciprocal multiplication.
+fmul() {
+	printf '%s\n' "$((($(pot "$1") * $2 + $3 - 1) / $3))"
+}
+
+# Adjustment factor when a ceiling value is used.
+fadj() {
+	local i="$(gcd "$2" "$3")"
+	printf '%s\n' "$(($(pot "$1") * ($3 / i - 1) / ($3 / i)))"
+}
+
+# Compute the appropriate mul/adj values as well as a shift count,
+# which brings the mul value into the range 2^b-1 <= x < 2^b.  Such
+# a shift value will be correct in the signed integer range and off
+# by at most one in the upper half of the unsigned range.
+fmuls() {
+	local i=0
+    local j
+	while true; do
+        j="$(fmul "${i}" "$2" "$3")"
+		if [ "${j}" -ge "$(pot "$(($1 - 1))")" ]; then
+			printf '%s\n' "${i}" && return
+		fi
+		i="$((i + 1))"
+	done
+}
+
+printf '/* Automatically generated by kernel/time/timeconst.sh */\n'
+printf '/* Time conversion constants for HZ == %s */\n\n' "$1"
+
+printf '#ifndef KERNEL_TIMECONST_H\n'
+printf '#define KERNEL_TIMECONST_H\n\n'
+
+printf '#include <linux/param.h>\n'
+printf '#include <linux/types.h>\n\n'
+
+printf '#if HZ != %s\n' "$1"
+printf '#error "include/generated/timeconst.h has the wrong HZ value!"\n'
+printf '#endif\n\n'
+
+if [ "$1" -lt 2 ]; then
+	printf '#error Totally bogus HZ value!\n'
+	exit 1
+fi
+
+s="$(fmuls 32 1000 "$1")"
+printf '#define HZ_TO_MSEC_MUL32\tU64_C(0x%X)\n' "$(fmul "${s}" 1000 "$1")"
+printf '#define HZ_TO_MSEC_ADJ32\tU64_C(0x%X)\n' "$(fadj "${s}" 1000 "$1")"
+printf '#define HZ_TO_MSEC_SHR32\t%s\n' "${s}"
+
+s="$(fmuls 32 "$1" 1000)"
+printf '#define MSEC_TO_HZ_MUL32\tU64_C(0x%X)\n' "$(fmul "${s}" "$1" 1000)"
+printf '#define MSEC_TO_HZ_ADJ32\tU64_C(0x%X)\n' "$(fadj "${s}" "$1" 1000)"
+printf '#define MSEC_TO_HZ_SHR32\t%s\n' "${s}"
+
+cd="$(gcd "$1" 1000)"
+printf '#define HZ_TO_MSEC_NUM\t\t%s\n' "$((1000 / cd))"
+printf '#define HZ_TO_MSEC_DEN\t\t%s\n' "$((hz / cd))"
+printf '#define MSEC_TO_HZ_NUM\t\t%s\n' "$((hz / cd))"
+printf '#define MSEC_TO_HZ_DEN\t\t%s\n\n' "$((1000 / cd))"
+
+s="$(fmuls 32 1000000 "$1")"
+printf '#define HZ_TO_USEC_MUL32\tU64_C(0x%X)\n' "$(fmul "${s}" 1000000 "$1")"
+printf '#define HZ_TO_USEC_ADJ32\tU64_C(0x%X)\n' "$(fadj "${s}" 1000000 "$1")"
+printf '#define HZ_TO_USEC_SHR32\t%s\n' "${s}"
+
+s="$(fmuls 32 "$1" 1000000)"
+printf '#define USEC_TO_HZ_MUL32\tU64_C(0x%X)\n' "$(fmul "${s}" "$1" 1000000)"
+printf '#define USEC_TO_HZ_ADJ32\tU64_C(0x%X)\n' "$(fadj "${s}" "$1" 1000000)"
+printf '#define USEC_TO_HZ_SHR32\t%s\n' "${s}"
+
+cd="$(gcd "$1" 1000000)"
+printf '#define HZ_TO_USEC_NUM\t\t%s\n' "$((1000000 / cd))"
+printf '#define HZ_TO_USEC_DEN\t\t%s\n' "$((hz / cd))"
+printf '#define USEC_TO_HZ_NUM\t\t%s\n' "$((hz / cd))"
+printf '#define USEC_TO_HZ_DEN\t\t%s\n' "$((1000000 / cd))"
+
+cd="$(gcd "$1" 1000000000)"
+printf '#define HZ_TO_NSEC_NUM\t\t%s\n' "$((1000000000 / cd))"
+printf '#define HZ_TO_NSEC_DEN\t\t%s\n' "$((hz / cd))"
+printf '#define NSEC_TO_HZ_NUM\t\t%s\n' "$((hz / cd))"
+printf '#define NSEC_TO_HZ_DEN\t\t%s\n' "$((1000000000 / cd))"
+
+printf '\n#endif /* KERNEL_TIMECONST_H */\n'
-- 
2.22.0

Re: [PATCH v2] replace timeconst bc script with an sh script

[Borislav Petkov]

On Thu, Jun 20, 2019 at 04:11:32AM -0400, Ethan Sommer wrote:
> removes the bc build dependency introduced when timeconst.pl was
> replaced by timeconst.bc:
> 70730bca1331 ("kernel: Replace timeconst.pl with a bc script")

I don't see you answering Kieran's questions anywhere...

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Mary Higgins, Sri Rasiah, HRB 21284 (AG Nürnberg)

Re: [PATCH v2] replace timeconst bc script with an sh script

[Ethan Sommer]

(resend because I didn't know gmail would make it html)
Ah sorry about that, I accidentally replied to Kieran only instead of
to all, my response was "I will upload a patch with those issues fixed
shortly, in terms of the dependency as far as I know commands only required
for running tests don't count as kernel compilation dependencies, and I
don't see any other uses of bc except for Documentation/EDID/Makefile, so
I believe that bc can be removed from the kernel compilation section of the
process document and will include that change with the updated patch that
fixes the 2 issues you pointed out."

On Thu, Jun 20, 2019 at 4:26 AM Borislav Petkov <bp@suse.de> wrote:
>
> On Thu, Jun 20, 2019 at 04:11:32AM -0400, Ethan Sommer wrote:
> > removes the bc build dependency introduced when timeconst.pl was
> > replaced by timeconst.bc:
> > 70730bca1331 ("kernel: Replace timeconst.pl with a bc script")
>
> I don't see you answering Kieran's questions anywhere...
>
> --
> Regards/Gruss,
>     Boris.
>
> SUSE Linux GmbH, GF: Felix Imendörffer, Mary Higgins, Sri Rasiah, HRB 21284 (AG Nürnberg)

Re: [PATCH v2] replace timeconst bc script with an sh script

[Borislav Petkov]

On Thu, Jun 20, 2019 at 04:29:19AM -0400, Ethan Sommer wrote:
> Ah sorry about that, I accidentally replied to Kieran only instead of to
> all, my response was "I will upload a patch with those issues fixed
> shortly, in terms of the dependency as far as I know commands only required
> for running tests don't count as kernel compilation dependencies, and I
> don't see any other uses of bc except for Documentation/EDID/Makefile, so I
> believe that bc can be removed from the kernel compilation section of the
> process document and will include that change with the updated patch that
> fixes the 2 issues you pointed out."

Sounds like parts of it should be in your commit message as a
justification *why* you're doing it. You can do that for your next
revision once you've waited a couple of days to gather feedback.

Also, please do not top-post.

Thx.

-- 
Regards/Gruss,
    Boris.

SUSE Linux GmbH, GF: Felix Imendörffer, Mary Higgins, Sri Rasiah, HRB 21284 (AG Nürnberg)