From 9c01ceb5769ff67cc26f4d133c059246d53c5089 Mon Sep 17 00:00:00 2001
From: Ben Gras <ben@minix3.org>
Date: Mon, 4 Jul 2011 02:51:12 +0200
Subject: [PATCH] introduce sqrt_approx() in -lsys

  . use this to avoid -lm dependency in mfs
---
 common/include/minix/sysutil.h |  1 +
 lib/libsys/Makefile            |  2 ++
 lib/libsys/sqrt_approx.c       | 14 ++++++++++++++
 servers/mfs/Makefile           |  2 +-
 servers/mfs/cache.c            |  2 +-
 5 files changed, 19 insertions(+), 2 deletions(-)
 create mode 100644 lib/libsys/sqrt_approx.c

diff --git a/common/include/minix/sysutil.h b/common/include/minix/sysutil.h
index 67dc218ab..c40e89189 100644
--- a/common/include/minix/sysutil.h
+++ b/common/include/minix/sysutil.h
@@ -65,6 +65,7 @@ _PROTOTYPE( u32_t tsc_get_khz, (void));
 _PROTOTYPE( u32_t micros_to_ticks, (u32_t micros));
 _PROTOTYPE( void ser_putc, (char c));
 _PROTOTYPE( void get_randomness, (struct k_randomness *, int));
+_PROTOTYPE( u32_t sqrt_approx, (u32_t));
 
 #define asynsend(ep, msg) asynsend3(ep, msg, 0)
 _PROTOTYPE( int asynsend3, (endpoint_t ep, message *msg, int flags));
diff --git a/lib/libsys/Makefile b/lib/libsys/Makefile
index 069c3ae54..f5bdc73bc 100644
--- a/lib/libsys/Makefile
+++ b/lib/libsys/Makefile
@@ -57,6 +57,7 @@ SRCS=  \
 	sef_signal.c \
 	ser_putc.c \
 	spin.c \
+	sqrt_approx.c \
 	stacktrace.c \
 	sys_abort.c \
 	sys_clear.c \
@@ -127,6 +128,7 @@ SRCS=  \
 	vm_yield_get_block.c \
 	vprintf.c \
 
+
 CPPFLAGS.sched_start.c+=	-I${MINIXSRCDIR}
 
 .if (${NBSD_LIBC} != "no")
diff --git a/lib/libsys/sqrt_approx.c b/lib/libsys/sqrt_approx.c
new file mode 100644
index 000000000..07eeaec4f
--- /dev/null
+++ b/lib/libsys/sqrt_approx.c
@@ -0,0 +1,14 @@
+#include <minix/sysutil.h>
+
+u32_t sqrt_approx(u32_t in)
+{
+        int b, v = 0;
+        for(b = (sizeof(in)*8)/2-1; b >= 0; b--) {
+                u32_t n = v | (1UL << b);
+                if(n*n <= in)
+                        v = n;
+        }
+
+        return v;
+}
+
diff --git a/servers/mfs/Makefile b/servers/mfs/Makefile
index e893c37b5..3730c4400 100644
--- a/servers/mfs/Makefile
+++ b/servers/mfs/Makefile
@@ -6,7 +6,7 @@ SRCS=	cache.c device.c link.c \
 	write.c inode.c main.c path.c super.c
 
 DPADD+=	${LIBM} ${LIBSYS}
-LDADD+=	-lm -lsys
+LDADD+= -lsys
 
 MAN=
 
diff --git a/servers/mfs/cache.c b/servers/mfs/cache.c
index 2833f94dd..7ff36d0a4 100644
--- a/servers/mfs/cache.c
+++ b/servers/mfs/cache.c
@@ -601,7 +601,7 @@ PRIVATE int bufs_heuristic(struct super_block *sp)
   /* heuristic for a desired cache size based on FS usage;
    * but never bigger than half of the total filesystem
    */
-  kb_fsmax = sqrt(kbytes_used_fs)*40;
+  kb_fsmax = sqrt_approx(kbytes_used_fs)*40;
   kb_fsmax = MIN(kb_fsmax, kbytes_total_fs/2);
 
   /* heuristic for a maximum usage - 10% of remaining memory */
-- 
2.44.0