From daeeb5aca3a18ff8e240a534bad1f0941523cf9c Mon Sep 17 00:00:00 2001
From: George Koehler <xkernigh@netscape.net>
Date: Sat, 5 Nov 2016 21:29:03 -0400
Subject: [PATCH] Simplify flt_arith now that mantissa uses uint32_t.

It seems that someone wanted to build flt_arith with a compiler that
had long but not unsigned long.  This required extra code to
accomplish unsigned right shift, unsigned division, and unsigned
comparison using the signed operations.  Now that we use uint32_t, we
can simply use the unsigned operations and remove the ucmp() function.
We have similar code in mach/proto/fp/ and in
lang/cem/libcc.ansi/stdlib/ext_comp.c where we use the unsigned
operations.

Some long variables become uint32_t, and some masks with 0xFFFFFFFF
disappear because uint32_t has only 32 bits.

Update flt_arith.3 to show that mantissa uses uint32_t.

Provide a target to install modules/src/flt_arith/test.c as flt_test
so I can run the tests.
---
 modules/src/flt_arith/b64_add.c   | 10 +++----
 modules/src/flt_arith/b64_sft.c   | 15 ++++------
 modules/src/flt_arith/build.lua   | 15 +++++++++-
 modules/src/flt_arith/flt_add.c   |  9 +++---
 modules/src/flt_arith/flt_arith.3 |  4 +--
 modules/src/flt_arith/flt_div.c   | 47 +++++++++++++------------------
 modules/src/flt_arith/flt_misc.h  |  2 --
 modules/src/flt_arith/flt_mul.c   | 13 +++++----
 modules/src/flt_arith/flt_nrm.c   |  5 ++--
 modules/src/flt_arith/test.c      |  5 +++-
 modules/src/flt_arith/ucmp.c      | 21 --------------
 11 files changed, 64 insertions(+), 82 deletions(-)
 delete mode 100644 modules/src/flt_arith/ucmp.c

diff --git a/modules/src/flt_arith/b64_add.c b/modules/src/flt_arith/b64_add.c
index ca03e84a0..71bd66607 100644
--- a/modules/src/flt_arith/b64_add.c
+++ b/modules/src/flt_arith/b64_add.c
@@ -5,6 +5,7 @@
 
 /* $Id$ */
 
+#include <stdint.h>
 #include "flt_misc.h"
 
 int
@@ -15,16 +16,15 @@ flt_b64_add(e1,e2)
 	int	carry;
 
 	/* add higher pair of 32 bits */
-	overflow = ucmp((long)0xFFFFFFFF - e1->flt_h_32, e2->flt_h_32) < 0;
+	overflow = (0xFFFFFFFFUL - e1->flt_h_32 < e2->flt_h_32);
 	e1->flt_h_32 += e2->flt_h_32;
 
 	/* add lower pair of 32 bits */
-	carry = ucmp((long)0xFFFFFFFF - e1->flt_l_32, e2->flt_l_32) < 0;
+	carry = (0xFFFFFFFFUL - e1->flt_l_32 < e2->flt_l_32);
 	e1->flt_l_32 += e2->flt_l_32;
 
-	if ((carry) && ((++e1->flt_h_32 &~0xFFFFFFFF) || e1->flt_h_32 == 0)) {
-		e1->flt_h_32 = 0;
+	if ((carry) && (++e1->flt_h_32 == 0))
 		return(1);		/* had a 64 bit overflow */
-	}
+
 	return(overflow);	/* return status from higher add */
 }
diff --git a/modules/src/flt_arith/b64_sft.c b/modules/src/flt_arith/b64_sft.c
index f891c6936..ef6d74a9e 100644
--- a/modules/src/flt_arith/b64_sft.c
+++ b/modules/src/flt_arith/b64_sft.c
@@ -23,12 +23,10 @@ flt_b64_sft(e,n)
 		n -= 32;
 	}
 	if (n > 0) {
-		e->flt_l_32 = (e->flt_l_32 >> 1) & 0x7FFFFFFF;
-		e->flt_l_32 >>= (n - 1);
+		e->flt_l_32 >>= n;
 		if (e->flt_h_32 != 0) {
-			e->flt_l_32 |= (e->flt_h_32 << (32 - n)) & 0xFFFFFFFF;
-			e->flt_h_32 = (e->flt_h_32 >> 1) & 0x7FFFFFFF;
-			e->flt_h_32 >>= (n - 1);
+			e->flt_l_32 |= (e->flt_h_32 << (32 - n));
+			e->flt_h_32 >>= n;
 		}
 	}
 	n = -n;
@@ -38,11 +36,10 @@ flt_b64_sft(e,n)
 		n -= 32;
 	}
 	if (n > 0) {
-		e->flt_h_32 = (e->flt_h_32 << n) & 0xFFFFFFFF;
+		e->flt_h_32 <<= n;
 		if (e->flt_l_32 != 0) {
-			long l = (e->flt_l_32 >> 1) & 0x7FFFFFFF;
-			e->flt_h_32 |= (l >> (31 - n));
-			e->flt_l_32 = (e->flt_l_32 << n) & 0xFFFFFFFF;
+			e->flt_h_32 |= (e->flt_l_32 >> (32 - n));
+			e->flt_l_32 <<= n;
 		}
 	}
 }
diff --git a/modules/src/flt_arith/build.lua b/modules/src/flt_arith/build.lua
index e6ac2dd40..54aa3b097 100644
--- a/modules/src/flt_arith/build.lua
+++ b/modules/src/flt_arith/build.lua
@@ -15,7 +15,6 @@ clibrary {
 		"./flt_umin.c",
 		"./flt_chk.c",
 		"./split.c",
-		"./ucmp.c",
 	},
 	hdrs = { "./flt_arith.h" },
 	deps = {
@@ -24,4 +23,18 @@ clibrary {
 	}
 }
 
+-- The test program isn't built by default.  Here is a target
+-- modules/src/flt_arith+pkg to install it as flt_test
 
+cprogram {
+	name = "test",
+	srcs = { "./test.c" },
+	deps = { "+lib" },
+}
+
+installable {
+	name = "pkg",
+	map = {
+		["$(INSDIR)/bin/flt_test"] = "+test",
+	},
+}
diff --git a/modules/src/flt_arith/flt_add.c b/modules/src/flt_arith/flt_add.c
index d9d4d57c5..ca9830ec3 100644
--- a/modules/src/flt_arith/flt_add.c
+++ b/modules/src/flt_arith/flt_add.c
@@ -44,11 +44,10 @@ flt_add(e1,e2,e3)
 	}
 	if (e1->flt_sign != e2->flt_sign) {
 		/* e2 + e1 = e2 - (-e1) */
-		int tmp = ucmp(e1->m1, e2->m1);
-		int tmp2 = ucmp(e1->m2, e2->m2);
-		if (tmp > 0 || (tmp == 0 && tmp2 > 0)) {
+		if (e1->m1 > e2->m1 ||
+		    (e1->m1 == e2->m1 && e1->m2 > e2->m2)) {
                 	/*      abs(e1) > abs(e2) */
-                	if (tmp2 < 0) {
+			if (e1->m2 < e2->m2) {
                         	e1->m1 -= 1;    /* carry in */
                 	}
                 	e1->m1 -= e2->m1;
@@ -56,7 +55,7 @@ flt_add(e1,e2,e3)
                 	*e3 = *e1;
         	}
         	else {
-                	if (tmp2 > 0)
+			if (e1->m2 > e2->m2)
                         	e2->m1 -= 1;    /* carry in */
                 	e2->m1 -= e1->m1;
                 	e2->m2 -= e1->m2;
diff --git a/modules/src/flt_arith/flt_arith.3 b/modules/src/flt_arith/flt_arith.3
index 2e6a5feb1..91bce44ea 100644
--- a/modules/src/flt_arith/flt_arith.3
+++ b/modules/src/flt_arith/flt_arith.3
@@ -9,8 +9,8 @@ flt_arith \- high precision floating point arithmetic
 .if t .ta 3m 13m 22m
 .if n .ta 5m 25m 40m
 struct flt_mantissa {
-	long	flt_h_32;	/* high order 32 bits of mantissa */
-	long	flt_l_32;	/* low order 32 bits of mantissa */
+	uint32_t flt_h_32;	/* high order 32 bits of mantissa */
+	uint32_t flt_l_32;	/* low order 32 bits of mantissa */
 };
 
 typedef struct {
diff --git a/modules/src/flt_arith/flt_div.c b/modules/src/flt_arith/flt_div.c
index 11b74c0e1..3295fe63b 100644
--- a/modules/src/flt_arith/flt_div.c
+++ b/modules/src/flt_arith/flt_div.c
@@ -5,14 +5,15 @@
 
 /* $Id$ */
 
+#include <stdint.h>
 #include "flt_misc.h"
 
 void
 flt_div(e1,e2,e3)
 	register flt_arith *e1,*e2,*e3;
 {
-	long	result[2];
-	register long	*lp;
+	uint32_t result[2];
+	register uint32_t *rp;
 	unsigned short u[9], v[5];
 	register int j;
 	register unsigned short *u_p = u;
@@ -44,7 +45,7 @@ flt_div(e1,e2,e3)
 	while (! v[maxv]) maxv--;
 	result[0] = 0;
 	result[1] = 0;
-	lp = result;
+	rp = result;
 
 	/*
 	 * Use an algorithm of Knuth (The art of programming, Seminumerical
@@ -52,35 +53,25 @@ flt_div(e1,e2,e3)
 	 * with base 65536. 
 	 */
 	for (j = 0; j <= 3; j++, u_p++) {
-		long q_est, temp;
-		long v1 = v[1];
+		uint32_t q_est, temp;
 
-		if (j == 2) lp++;
+		if (j == 2) rp++;
 		if (u_p[0] == 0 && u_p[1] < v[1]) continue;
-		temp = ((long)u_p[0] << 16) + u_p[1];
+		temp = ((uint32_t)u_p[0] << 16) + u_p[1];
 		if (u_p[0] >= v[1]) {
-			q_est = 0x0000FFFFL;
+			q_est = 0x0000FFFFUL;
 		}
 		else if (v[1] == 1) {
 			q_est = temp;
 		}
-		else if (temp >= 0) {
-			q_est = temp / v1;
-		}
 		else {
-			long rem;
-			q_est = (0x7FFFFFFF/v1)+((temp&0x7FFFFFFF)/v1);
-			rem = (0x7FFFFFFF%v1)+((temp&0x7FFFFFFF)%v1)+1;
-			while (rem >= v1) {
-				q_est++;
-				rem -= v1;
-			}
+			q_est = temp / v[1];
 		}
-		temp -= q_est * v1;
+		temp -= q_est * v[1];
 		while (!(temp&0xFFFF0000) &&
-		       ucmp((long)v[2]*q_est,(temp<<16)+(long)u_p[2]) > 0) {
+		       v[2]*q_est > (temp<<16)+u_p[2]) {
 			q_est--;
-			temp += v1;
+			temp += v[1];
 		}
 		/*	Now, according to Knuth, we have an estimate of the
 			quotient, that is either correct or one too big, but
@@ -88,11 +79,11 @@ flt_div(e1,e2,e3)
 		*/
 		if (q_est != 0)  {
 			int i;
-			long k = 0;
+			uint32_t k = 0;
 			int borrow = 0;
 
 			for (i = maxv; i > 0; i--) {
-				long tmp = q_est * (long)v[i] + k + borrow;
+				uint32_t tmp = q_est * v[i] + k + borrow;
 				unsigned short md = tmp & 0xFFFF;
 
 				borrow = (md > u_p[i]);
@@ -100,7 +91,7 @@ flt_div(e1,e2,e3)
 				k = (tmp >> 16) & 0xFFFF;
 			}
 			k += borrow;
-			borrow = (long)u_p[0] < k;
+			borrow = u_p[0] < k;
 			u_p[0] -= k;
 
 			if (borrow) {
@@ -110,15 +101,15 @@ flt_div(e1,e2,e3)
 				q_est--;
 				borrow = 0;
 				for (i = maxv; i > 0; i--) {
-					long tmp 
-					    = v[i]+(long)u_p[i]+borrow;
-					
+					uint32_t tmp
+					    = v[i]+(uint32_t)u_p[i]+borrow;
+
 					u_p[i] = tmp & 0xFFFF;
 					borrow = (tmp >> 16) & 0xFFFF;
 				}
 				u_p[0] += borrow;
 			}
-			*lp |= (j & 1) ? q_est : (q_est<<16);
+			*rp |= (j & 1) ? q_est : (q_est<<16);
 		}
 	}
 	e3->m1 = result[0];
diff --git a/modules/src/flt_arith/flt_misc.h b/modules/src/flt_arith/flt_misc.h
index c5cf5a7cf..64b6865aa 100644
--- a/modules/src/flt_arith/flt_misc.h
+++ b/modules/src/flt_arith/flt_misc.h
@@ -15,13 +15,11 @@
 #define EXT_MIN		(-16384)	/* min exponent */
 
 /* hiding of names: */
-#define ucmp		_flt_ucmp
 #define flt_nrm		_flt_nrm
 #define flt_chk		_flt_chk
 #define flt_b64_add	_flt_64add
 #define flt_split	_flt_split
 
-int ucmp(long, long);
 void flt_nrm(flt_arith *);
 void flt_chk(flt_arith *);
 int flt_b64_add(struct flt_mantissa *, struct flt_mantissa *);
diff --git a/modules/src/flt_arith/flt_mul.c b/modules/src/flt_arith/flt_mul.c
index e6972ab54..4d989382b 100644
--- a/modules/src/flt_arith/flt_mul.c
+++ b/modules/src/flt_arith/flt_mul.c
@@ -5,6 +5,7 @@
 
 /* $Id$ */
 
+#include <stdint.h>
 #include "flt_misc.h"
 
 void
@@ -43,9 +44,9 @@ flt_mul(e1,e2,e3)
 	 */
 	for(i=4, pres = &result[4];i--;pres--) if (mp[i]) {
 		unsigned short k = 0;
-		long mpi = mp[i];
+		uint32_t mpi = mp[i];
 		for(j=4;j--;) {
-			long tmp = (long)pres[j] + k;
+			long tmp = (uint32_t)pres[j] + k;
 			if (mc[j]) tmp += mpi * mc[j];
 			pres[j] = tmp & 0xFFFF;
 			k = (tmp >> 16) & 0xFFFF;
@@ -64,12 +65,12 @@ flt_mul(e1,e2,e3)
 	/*
 	 *	combine the registers to a total
 	 */
-	e3->m1 = ((long)result[0] << 16) + result[1];
-	e3->m2 = ((long)result[2] << 16) + result[3];
+	e3->m1 = ((uint32_t)result[0] << 16) + result[1];
+	e3->m2 = ((uint32_t)result[2] << 16) + result[3];
 	if (result[4] & 0x8000) {
-		if (++e3->m2 == 0 || (e3->m2 & ~ 0xFFFFFFFF)) {
+		if (++e3->m2 == 0) {
 			e3->m2 = 0;
-			if (++e3->m1 == 0 || (e3->m1 & ~ 0xFFFFFFFF)) {
+			if (++e3->m1 == 0) {
 				e3->m1 = 0x80000000;
 				e3->flt_exp++;
 			}
diff --git a/modules/src/flt_arith/flt_nrm.c b/modules/src/flt_arith/flt_nrm.c
index 14762b616..3520ee5b4 100644
--- a/modules/src/flt_arith/flt_nrm.c
+++ b/modules/src/flt_arith/flt_nrm.c
@@ -5,6 +5,7 @@
 
 /* $Id$ */
 
+#include <stdint.h>
 #include "flt_misc.h"
 
 void
@@ -24,8 +25,8 @@ flt_nrm(e)
 		e->m2 = 0L;
 		e->flt_exp -= 32;
 	}
-	if ((e->m1 & 0x80000000) == 0) {
-		long l = 0x40000000;
+	if ((e->m1 & 0x80000000UL) == 0) {
+		uint32_t l = 0x40000000UL;
 		int cnt = -1;
 
 		while (! (l & e->m1)) {
diff --git a/modules/src/flt_arith/test.c b/modules/src/flt_arith/test.c
index bf9c43c69..dfc4a694a 100644
--- a/modules/src/flt_arith/test.c
+++ b/modules/src/flt_arith/test.c
@@ -1,3 +1,5 @@
+#include <stdio.h>
+#include <string.h>
 #include "flt_arith.h"
 
 struct tests {
@@ -22,6 +24,7 @@ struct tests {
 	{ 0, 0, 0, 0}
 };
 
+int
 main()
 {
 	register struct tests *p = tests;
@@ -31,7 +34,7 @@ main()
 		if (! dotest(p)) exit_status = 1;
 		p++;
 	}
-	exit(exit_status);
+	return exit_status;
 }
 
 int
diff --git a/modules/src/flt_arith/ucmp.c b/modules/src/flt_arith/ucmp.c
deleted file mode 100644
index c4b7bc0a4..000000000
--- a/modules/src/flt_arith/ucmp.c
+++ /dev/null
@@ -1,21 +0,0 @@
-/*
-  (c) copyright 1989 by the Vrije Universiteit, Amsterdam, The Netherlands.
-  See the copyright notice in the ACK home directory, in the file "Copyright".
-*/
-
-/* $Id$ */
-
-#include "flt_misc.h"
-
-int
-ucmp(l1,l2)
-	long l1,l2;
-{
-	if (l1 == l2) return 0;
-	if (l2 >= 0) {
-		if (l1 > l2 || l1 < 0) return 1;
-		return -1;
-	}
-	if (l1 >= 0 || l1 < l2) return -1;
-	return 1;
-}