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[PATCH] Clean up comments in mpa.c
- From: Siddhesh Poyarekar <siddhesh at redhat dot com>
- To: libc-alpha at sourceware dot org
- Date: Fri, 4 Jan 2013 18:22:19 +0530
- Subject: [PATCH] Clean up comments in mpa.c
Hi,
Attached patch cleans up the comments in mpa.c (global as well as the
powerpc ones). Main changes are style based, although I have reworded
most of them. This is a precursor to a code style change that I
intend to post once this patch is in. OK to commit?
Siddhesh
* sysdeps/ieee754/dbl-64/mpa.c (mcr): Reword comment.
(__acr): Likewise.
(__cpy): Likewise.
(norm): Likewise.
(denorm): Likewise.
(__mp_dbl): Likewise.
(__dbl_mp): Likewise.
(add_magnitudes): Likewise.
(sub_magnitudes): Likewise.
(__add): Likewise.
(__sub): Likewise.
(__mul): Likewise.
(__inv): Likewise.
(__dvd): Likewise.
* sysdeps/powerpc/powerpc32/power4/fpu/mpa.c (mcr): Likewise.
(__acr): Likewise.
(__cpy): Likewise.
(norm): Likewise.
(denorm): Likewise.
(__mp_dbl): Likewise.
(__dbl_mp): Likewise.
(add_magnitudes): Likewise.
(sub_magnitudes): Likewise.
(__add): Likewise.
(__sub): Likewise.
(__mul): Likewise.
(__inv): Likewise.
(__dvd): Likewise.
* sysdeps/powerpc/powerpc64/power4/fpu/mpa.c (mcr): Likewise.
(__acr): Likewise.
(__cpy): Likewise.
(norm): Likewise.
(denorm): Likewise.
(__mp_dbl): Likewise.
(__dbl_mp): Likewise.
(add_magnitudes): Likewise.
(sub_magnitudes): Likewise.
(__add): Likewise.
(__sub): Likewise.
(__mul): Likewise.
(__inv): Likewise.
(__dvd): Likewise.
diff --git a/sysdeps/ieee754/dbl-64/mpa.c b/sysdeps/ieee754/dbl-64/mpa.c
index b0571f9..7abad67 100644
--- a/sysdeps/ieee754/dbl-64/mpa.c
+++ b/sysdeps/ieee754/dbl-64/mpa.c
@@ -45,7 +45,7 @@
#include "endian.h"
#include "mpa.h"
#include "mpa2.h"
-#include <sys/param.h> /* For MIN() */
+#include <sys/param.h>
#ifndef SECTION
# define SECTION
@@ -57,10 +57,8 @@ const mp_no mptwo = {1, {1.0, 2.0}};
#endif
#ifndef NO___ACR
-/* mcr() compares the sizes of the mantissas of two multiple precision */
-/* numbers. Mantissas are compared regardless of the signs of the */
-/* numbers, even if x->d[0] or y->d[0] are zero. Exponents are also */
-/* disregarded. */
+/* Compare mantissa of two multiple precision numbers regardless of the sign
+ and exponent of the numbers. */
static int
mcr(const mp_no *x, const mp_no *y, int p) {
int i;
@@ -71,8 +69,7 @@ mcr(const mp_no *x, const mp_no *y, int p) {
return 0;
}
-
-/* acr() compares the absolute values of two multiple precision numbers */
+/* Compare the absolute values of two multiple precision numbers. */
int
__acr(const mp_no *x, const mp_no *y, int p) {
int i;
@@ -92,19 +89,18 @@ __acr(const mp_no *x, const mp_no *y, int p) {
}
#endif
-
#ifndef NO___CPY
-/* Copy a multiple precision number. Set *y=*x. x=y is permissible. */
+/* Copy multiple precision number X into Y. They could be the same
+ number. */
void __cpy(const mp_no *x, mp_no *y, int p) {
EY = EX;
for (int i=0; i <= p; i++) Y[i] = X[i];
}
#endif
-
#ifndef NO___MP_DBL
-/* Convert a multiple precision number *x into a double precision */
-/* number *y, normalized case (|x| >= 2**(-1022))) */
+/* Convert a multiple precision number *X into a double precision
+ number *Y, normalized case (|x| >= 2**(-1022))). */
static void norm(const mp_no *x, double *y, int p)
{
#define R RADIXI
@@ -154,8 +150,8 @@ static void norm(const mp_no *x, double *y, int p)
#undef R
}
-/* Convert a multiple precision number *x into a double precision */
-/* number *y, denormalized case (|x| < 2**(-1022))) */
+/* Convert a multiple precision number *X into a double precision
+ number *Y, Denormal case (|x| < 2**(-1022))). */
static void denorm(const mp_no *x, double *y, int p)
{
int i,k;
@@ -198,9 +194,8 @@ static void denorm(const mp_no *x, double *y, int p)
#undef R
}
-/* Convert a multiple precision number *x into a double precision number *y. */
-/* The result is correctly rounded to the nearest/even. *x is left unchanged */
-
+/* Convert multiple precision number *X into double precision number *Y. The
+ result is correctly rounded to the nearest/even. */
void __mp_dbl(const mp_no *x, double *y, int p) {
if (X[0] == ZERO) {*y = ZERO; return; }
@@ -212,11 +207,8 @@ void __mp_dbl(const mp_no *x, double *y, int p) {
}
#endif
-
-/* dbl_mp() converts a double precision number x into a multiple precision */
-/* number *y. If the precision p is too small the result is truncated. x is */
-/* left unchanged. */
-
+/* Get the multiple precision equivalent of X into *Y. If the precision is too
+ small, the result is truncated. */
void
SECTION
__dbl_mp(double x, mp_no *y, int p) {
@@ -224,16 +216,16 @@ __dbl_mp(double x, mp_no *y, int p) {
int i,n;
double u;
- /* Sign */
+ /* Sign. */
if (x == ZERO) {Y[0] = ZERO; return; }
else if (x > ZERO) Y[0] = ONE;
else {Y[0] = MONE; x=-x; }
- /* Exponent */
+ /* Exponent. */
for (EY=ONE; x >= RADIX; EY += ONE) x *= RADIXI;
for ( ; x < ONE; EY -= ONE) x *= RADIX;
- /* Digits */
+ /* Digits. */
n=MIN(p,4);
for (i=1; i<=n; i++) {
u = (x + TWO52) - TWO52;
@@ -242,13 +234,10 @@ __dbl_mp(double x, mp_no *y, int p) {
for ( ; i<=p; i++) Y[i] = ZERO;
}
-
-/* add_magnitudes() adds the magnitudes of *x & *y assuming that */
-/* abs(*x) >= abs(*y) > 0. */
-/* The sign of the sum *z is undefined. x&y may overlap but not x&z or y&z. */
-/* No guard digit is used. The result equals the exact sum, truncated. */
-/* *x & *y are left unchanged. */
-
+/* Add magnitudes of *X and *Y assuming that abs (*X) >= abs (*Y) > 0. The
+ sign of the sum *Z is not changed. X and Y may overlap but not X and Z or
+ Y and Z. No guard digit is used. The result equals the exact sum,
+ truncated. */
static void
SECTION
add_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
@@ -286,13 +275,10 @@ add_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
else EZ += ONE;
}
-
-/* sub_magnitudes() subtracts the magnitudes of *x & *y assuming that */
-/* abs(*x) > abs(*y) > 0. */
-/* The sign of the difference *z is undefined. x&y may overlap but not x&z */
-/* or y&z. One guard digit is used. The error is less than one ulp. */
-/* *x & *y are left unchanged. */
-
+/* Subtract the magnitudes of *X and *Y assuming that abs (*x) > abs (*y) > 0.
+ The sign of the difference *Z is not changed. X and Y may overlap but not X
+ and Z or Y and Z. One guard digit is used. The error is less than one
+ ULP. */
static void
SECTION
sub_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
@@ -344,11 +330,9 @@ sub_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
Z[k++] = ZERO;
}
-
-/* Add two multiple precision numbers. Set *z = *x + *y. x&y may overlap */
-/* but not x&z or y&z. One guard digit is used. The error is less than */
-/* one ulp. *x & *y are left unchanged. */
-
+/* Add *X and *Y and store the result in *Z. X and Y may overlap, but not X
+ and Z or Y and Z. One guard digit is used. The error is less than one
+ ULP. */
void
SECTION
__add(const mp_no *x, const mp_no *y, mp_no *z, int p) {
@@ -369,11 +353,9 @@ __add(const mp_no *x, const mp_no *y, mp_no *z, int p) {
}
}
-
-/* Subtract two multiple precision numbers. *z is set to *x - *y. x&y may */
-/* overlap but not x&z or y&z. One guard digit is used. The error is */
-/* less than one ulp. *x & *y are left unchanged. */
-
+/* Subtract *Y from *X and return the result in *Z. X and Y may overlap but
+ not X and Z or Y and Z. One guard digit is used. The error is less than
+ one ULP. */
void
SECTION
__sub(const mp_no *x, const mp_no *y, mp_no *z, int p) {
@@ -394,12 +376,9 @@ __sub(const mp_no *x, const mp_no *y, mp_no *z, int p) {
}
}
-
-/* Multiply two multiple precision numbers. *z is set to *x * *y. x&y */
-/* may overlap but not x&z or y&z. In case p=1,2,3 the exact result is */
-/* truncated to p digits. In case p>3 the error is bounded by 1.001 ulp. */
-/* *x & *y are left unchanged. */
-
+/* Multiply *X and *Y and store result in *Z. X and Y may overlap but not X
+ and Z or Y and Z. For P in [1, 2, 3], the exact result is truncated to P
+ digits. In case P > 3 the error is bounded by 1.001 ULP. */
void
SECTION
__mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
@@ -414,7 +393,7 @@ __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
- /* Multiply, add and carry */
+ /* Multiply, add and carry. */
k2 = (__glibc_unlikely (p < 3)) ? p + p : p + 3;
Z[k2] = ZERO;
@@ -443,7 +422,7 @@ __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
}
EZ = EX + EY;
- /* Is there a carry beyond the most significant digit? */
+ /* Is there a carry beyond the most significant digit? */
if (__glibc_unlikely (Z[1] == ZERO))
{
for (i = 1; i <= p; i++)
@@ -454,12 +433,12 @@ __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
Z[0] = X[0] * Y[0];
}
+/* Invert *X and store in *Y. Relative error bound:
+ - For P = 2: 1.001 * R ^ (1 - P)
+ - For P = 3: 1.063 * R ^ (1 - P)
+ - For P > 3: 2.001 * R ^ (1 - P)
-/* Invert a multiple precision number. Set *y = 1 / *x. */
-/* Relative error bound = 1.001*r**(1-p) for p=2, 1.063*r**(1-p) for p=3, */
-/* 2.001*r**(1-p) for p>3. */
-/* *x=0 is not permissible. *x is left unchanged. */
-
+ *X = 0 is not permissible. */
static
SECTION
void __inv(const mp_no *x, mp_no *y, int p) {
@@ -480,12 +459,13 @@ void __inv(const mp_no *x, mp_no *y, int p) {
}
}
+/* Divide *X by *Y and store result in *Z. X and Y may overlap but not X and Z
+ or Y and Z. Relative error bound:
+ - For P = 2: 2.001 * R ^ (1 - P)
+ - For P = 3: 2.063 * R ^ (1 - P)
+ - For P > 3: 3.001 * R ^ (1 - P)
-/* Divide one multiple precision number by another.Set *z = *x / *y. *x & *y */
-/* are left unchanged. x&y may overlap but not x&z or y&z. */
-/* Relative error bound = 2.001*r**(1-p) for p=2, 2.063*r**(1-p) for p=3 */
-/* and 3.001*r**(1-p) for p>3. *y=0 is not permissible. */
-
+ *X = 0 is not permissible. */
void
SECTION
__dvd(const mp_no *x, const mp_no *y, mp_no *z, int p) {
diff --git a/sysdeps/powerpc/powerpc32/power4/fpu/mpa.c b/sysdeps/powerpc/powerpc32/power4/fpu/mpa.c
index 449a745..2c792dd 100644
--- a/sysdeps/powerpc/powerpc32/power4/fpu/mpa.c
+++ b/sysdeps/powerpc/powerpc32/power4/fpu/mpa.c
@@ -46,11 +46,9 @@
#include "endian.h"
#include "mpa.h"
#include "mpa2.h"
-#include <sys/param.h> /* For MIN() */
-/* mcr() compares the sizes of the mantissas of two multiple precision */
-/* numbers. Mantissas are compared regardless of the signs of the */
-/* numbers, even if x->d[0] or y->d[0] are zero. Exponents are also */
-/* disregarded. */
+#include <sys/param.h>
+/* Compare mantissa of two multiple precision numbers regardless of the sign
+ and exponent of the numbers. */
static int mcr(const mp_no *x, const mp_no *y, int p) {
long i;
long p2 = p;
@@ -61,9 +59,7 @@ static int mcr(const mp_no *x, const mp_no *y, int p) {
return 0;
}
-
-
-/* acr() compares the absolute values of two multiple precision numbers */
+/* Compare the absolute values of two multiple precision numbers. */
int __acr(const mp_no *x, const mp_no *y, int p) {
long i;
@@ -81,8 +77,8 @@ int __acr(const mp_no *x, const mp_no *y, int p) {
return i;
}
-
-/* Copy a multiple precision number. Set *y=*x. x=y is permissible. */
+/* Copy multiple precision number X into Y. They could be the same
+ number. */
void __cpy(const mp_no *x, mp_no *y, int p) {
long i;
@@ -92,9 +88,8 @@ void __cpy(const mp_no *x, mp_no *y, int p) {
return;
}
-
-/* Convert a multiple precision number *x into a double precision */
-/* number *y, normalized case (|x| >= 2**(-1022))) */
+/* Convert a multiple precision number *X into a double precision
+ number *Y, normalized case (|x| >= 2**(-1022))). */
static void norm(const mp_no *x, double *y, int p)
{
#define R radixi.d
@@ -145,8 +140,8 @@ static void norm(const mp_no *x, double *y, int p)
#undef R
}
-/* Convert a multiple precision number *x into a double precision */
-/* number *y, denormalized case (|x| < 2**(-1022))) */
+/* Convert a multiple precision number *X into a double precision
+ number *Y, Denormal case (|x| < 2**(-1022))). */
static void denorm(const mp_no *x, double *y, int p)
{
long i,k;
@@ -192,9 +187,8 @@ static void denorm(const mp_no *x, double *y, int p)
#undef R
}
-/* Convert a multiple precision number *x into a double precision number *y. */
-/* The result is correctly rounded to the nearest/even. *x is left unchanged */
-
+/* Convert multiple precision number *X into double precision number *Y. The
+ result is correctly rounded to the nearest/even. */
void __mp_dbl(const mp_no *x, double *y, int p) {
if (X[0] == ZERO) {*y = ZERO; return; }
@@ -204,27 +198,24 @@ void __mp_dbl(const mp_no *x, double *y, int p) {
else denorm(x,y,p);
}
-
-/* dbl_mp() converts a double precision number x into a multiple precision */
-/* number *y. If the precision p is too small the result is truncated. x is */
-/* left unchanged. */
-
+/* Get the multiple precision equivalent of X into *Y. If the precision is too
+ small, the result is truncated. */
void __dbl_mp(double x, mp_no *y, int p) {
long i,n;
long p2 = p;
double u;
- /* Sign */
+ /* Sign. */
if (x == ZERO) {Y[0] = ZERO; return; }
else if (x > ZERO) Y[0] = ONE;
else {Y[0] = MONE; x=-x; }
- /* Exponent */
+ /* Exponent. */
for (EY=ONE; x >= RADIX; EY += ONE) x *= RADIXI;
for ( ; x < ONE; EY -= ONE) x *= RADIX;
- /* Digits */
+ /* Digits. */
n=MIN(p2,4);
for (i=1; i<=n; i++) {
u = (x + TWO52) - TWO52;
@@ -234,13 +225,10 @@ void __dbl_mp(double x, mp_no *y, int p) {
return;
}
-
-/* add_magnitudes() adds the magnitudes of *x & *y assuming that */
-/* abs(*x) >= abs(*y) > 0. */
-/* The sign of the sum *z is undefined. x&y may overlap but not x&z or y&z. */
-/* No guard digit is used. The result equals the exact sum, truncated. */
-/* *x & *y are left unchanged. */
-
+/* Add magnitudes of *X and *Y assuming that abs (*X) >= abs (*Y) > 0. The
+ sign of the sum *Z is not changed. X and Y may overlap but not X and Z or
+ Y and Z. No guard digit is used. The result equals the exact sum,
+ truncated. */
static void add_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
long i,j,k;
@@ -277,13 +265,10 @@ static void add_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
else EZ += ONE;
}
-
-/* sub_magnitudes() subtracts the magnitudes of *x & *y assuming that */
-/* abs(*x) > abs(*y) > 0. */
-/* The sign of the difference *z is undefined. x&y may overlap but not x&z */
-/* or y&z. One guard digit is used. The error is less than one ulp. */
-/* *x & *y are left unchanged. */
-
+/* Subtract the magnitudes of *X and *Y assuming that abs (*x) > abs (*y) > 0.
+ The sign of the difference *Z is not changed. X and Y may overlap but not X
+ and Z or Y and Z. One guard digit is used. The error is less than one
+ ULP. */
static void sub_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
long i,j,k;
@@ -336,11 +321,9 @@ static void sub_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
-
-/* Add two multiple precision numbers. Set *z = *x + *y. x&y may overlap */
-/* but not x&z or y&z. One guard digit is used. The error is less than */
-/* one ulp. *x & *y are left unchanged. */
-
+/* Add *X and *Y and store the result in *Z. X and Y may overlap, but not X
+ and Z or Y and Z. One guard digit is used. The error is less than one
+ ULP. */
void __add(const mp_no *x, const mp_no *y, mp_no *z, int p) {
int n;
@@ -360,11 +343,9 @@ void __add(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
-
-/* Subtract two multiple precision numbers. *z is set to *x - *y. x&y may */
-/* overlap but not x&z or y&z. One guard digit is used. The error is */
-/* less than one ulp. *x & *y are left unchanged. */
-
+/* Subtract *Y from *X and return the result in *Z. X and Y may overlap but
+ not X and Z or Y and Z. One guard digit is used. The error is less than
+ one ULP. */
void __sub(const mp_no *x, const mp_no *y, mp_no *z, int p) {
int n;
@@ -384,12 +365,9 @@ void __sub(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
-
-/* Multiply two multiple precision numbers. *z is set to *x * *y. x&y */
-/* may overlap but not x&z or y&z. In case p=1,2,3 the exact result is */
-/* truncated to p digits. In case p>3 the error is bounded by 1.001 ulp. */
-/* *x & *y are left unchanged. */
-
+/* Multiply *X and *Y and store result in *Z. X and Y may overlap but not X
+ and Z or Y and Z. For P in [1, 2, 3], the exact result is truncated to P
+ digits. In case P > 3 the error is bounded by 1.001 ULP. */
void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
long i, i1, i2, j, k, k2;
@@ -407,12 +385,12 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
if (k > p2) {i1=k-p2; i2=p2+1; }
else {i1=1; i2=k; }
#if 1
- /* rearange this inner loop to allow the fmadd instructions to be
+ /* Rearrange this inner loop to allow the fmadd instructions to be
independent and execute in parallel on processors that have
dual symetrical FP pipelines. */
if (i1 < (i2-1))
{
- /* make sure we have at least 2 iterations */
+ /* Make sure we have at least 2 iterations. */
if (((i2 - i1) & 1L) == 1L)
{
/* Handle the odd iterations case. */
@@ -427,7 +405,7 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
zk += x->d[i]*y->d[j];
zk2 += x->d[i+1]*y->d[j-1];
}
- zk += zk2; /* final sum. */
+ zk += zk2; /* Final sum. */
}
else
{
@@ -447,7 +425,7 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
}
Z[k] = zk;
- /* Is there a carry beyond the most significant digit? */
+ /* Is there a carry beyond the most significant digit? */
if (Z[1] == ZERO) {
for (i=1; i<=p2; i++) Z[i]=Z[i+1];
EZ = EX + EY - 1; }
@@ -458,12 +436,12 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
+/* Invert *X and store in *Y. Relative error bound:
+ - For P = 2: 1.001 * R ^ (1 - P)
+ - For P = 3: 1.063 * R ^ (1 - P)
+ - For P > 3: 2.001 * R ^ (1 - P)
-/* Invert a multiple precision number. Set *y = 1 / *x. */
-/* Relative error bound = 1.001*r**(1-p) for p=2, 1.063*r**(1-p) for p=3, */
-/* 2.001*r**(1-p) for p>3. */
-/* *x=0 is not permissible. *x is left unchanged. */
-
+ *X = 0 is not permissible. */
void __inv(const mp_no *x, mp_no *y, int p) {
long i;
double t;
@@ -487,12 +465,13 @@ void __inv(const mp_no *x, mp_no *y, int p) {
return;
}
+/* Divide *X by *Y and store result in *Z. X and Y may overlap but not X and Z
+ or Y and Z. Relative error bound:
+ - For P = 2: 2.001 * R ^ (1 - P)
+ - For P = 3: 2.063 * R ^ (1 - P)
+ - For P > 3: 3.001 * R ^ (1 - P)
-/* Divide one multiple precision number by another.Set *z = *x / *y. *x & *y */
-/* are left unchanged. x&y may overlap but not x&z or y&z. */
-/* Relative error bound = 2.001*r**(1-p) for p=2, 2.063*r**(1-p) for p=3 */
-/* and 3.001*r**(1-p) for p>3. *y=0 is not permissible. */
-
+ *X = 0 is not permissible. */
void __dvd(const mp_no *x, const mp_no *y, mp_no *z, int p) {
mp_no w;
diff --git a/sysdeps/powerpc/powerpc64/power4/fpu/mpa.c b/sysdeps/powerpc/powerpc64/power4/fpu/mpa.c
index 449a745..2c792dd 100644
--- a/sysdeps/powerpc/powerpc64/power4/fpu/mpa.c
+++ b/sysdeps/powerpc/powerpc64/power4/fpu/mpa.c
@@ -46,11 +46,9 @@
#include "endian.h"
#include "mpa.h"
#include "mpa2.h"
-#include <sys/param.h> /* For MIN() */
-/* mcr() compares the sizes of the mantissas of two multiple precision */
-/* numbers. Mantissas are compared regardless of the signs of the */
-/* numbers, even if x->d[0] or y->d[0] are zero. Exponents are also */
-/* disregarded. */
+#include <sys/param.h>
+/* Compare mantissa of two multiple precision numbers regardless of the sign
+ and exponent of the numbers. */
static int mcr(const mp_no *x, const mp_no *y, int p) {
long i;
long p2 = p;
@@ -61,9 +59,7 @@ static int mcr(const mp_no *x, const mp_no *y, int p) {
return 0;
}
-
-
-/* acr() compares the absolute values of two multiple precision numbers */
+/* Compare the absolute values of two multiple precision numbers. */
int __acr(const mp_no *x, const mp_no *y, int p) {
long i;
@@ -81,8 +77,8 @@ int __acr(const mp_no *x, const mp_no *y, int p) {
return i;
}
-
-/* Copy a multiple precision number. Set *y=*x. x=y is permissible. */
+/* Copy multiple precision number X into Y. They could be the same
+ number. */
void __cpy(const mp_no *x, mp_no *y, int p) {
long i;
@@ -92,9 +88,8 @@ void __cpy(const mp_no *x, mp_no *y, int p) {
return;
}
-
-/* Convert a multiple precision number *x into a double precision */
-/* number *y, normalized case (|x| >= 2**(-1022))) */
+/* Convert a multiple precision number *X into a double precision
+ number *Y, normalized case (|x| >= 2**(-1022))). */
static void norm(const mp_no *x, double *y, int p)
{
#define R radixi.d
@@ -145,8 +140,8 @@ static void norm(const mp_no *x, double *y, int p)
#undef R
}
-/* Convert a multiple precision number *x into a double precision */
-/* number *y, denormalized case (|x| < 2**(-1022))) */
+/* Convert a multiple precision number *X into a double precision
+ number *Y, Denormal case (|x| < 2**(-1022))). */
static void denorm(const mp_no *x, double *y, int p)
{
long i,k;
@@ -192,9 +187,8 @@ static void denorm(const mp_no *x, double *y, int p)
#undef R
}
-/* Convert a multiple precision number *x into a double precision number *y. */
-/* The result is correctly rounded to the nearest/even. *x is left unchanged */
-
+/* Convert multiple precision number *X into double precision number *Y. The
+ result is correctly rounded to the nearest/even. */
void __mp_dbl(const mp_no *x, double *y, int p) {
if (X[0] == ZERO) {*y = ZERO; return; }
@@ -204,27 +198,24 @@ void __mp_dbl(const mp_no *x, double *y, int p) {
else denorm(x,y,p);
}
-
-/* dbl_mp() converts a double precision number x into a multiple precision */
-/* number *y. If the precision p is too small the result is truncated. x is */
-/* left unchanged. */
-
+/* Get the multiple precision equivalent of X into *Y. If the precision is too
+ small, the result is truncated. */
void __dbl_mp(double x, mp_no *y, int p) {
long i,n;
long p2 = p;
double u;
- /* Sign */
+ /* Sign. */
if (x == ZERO) {Y[0] = ZERO; return; }
else if (x > ZERO) Y[0] = ONE;
else {Y[0] = MONE; x=-x; }
- /* Exponent */
+ /* Exponent. */
for (EY=ONE; x >= RADIX; EY += ONE) x *= RADIXI;
for ( ; x < ONE; EY -= ONE) x *= RADIX;
- /* Digits */
+ /* Digits. */
n=MIN(p2,4);
for (i=1; i<=n; i++) {
u = (x + TWO52) - TWO52;
@@ -234,13 +225,10 @@ void __dbl_mp(double x, mp_no *y, int p) {
return;
}
-
-/* add_magnitudes() adds the magnitudes of *x & *y assuming that */
-/* abs(*x) >= abs(*y) > 0. */
-/* The sign of the sum *z is undefined. x&y may overlap but not x&z or y&z. */
-/* No guard digit is used. The result equals the exact sum, truncated. */
-/* *x & *y are left unchanged. */
-
+/* Add magnitudes of *X and *Y assuming that abs (*X) >= abs (*Y) > 0. The
+ sign of the sum *Z is not changed. X and Y may overlap but not X and Z or
+ Y and Z. No guard digit is used. The result equals the exact sum,
+ truncated. */
static void add_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
long i,j,k;
@@ -277,13 +265,10 @@ static void add_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
else EZ += ONE;
}
-
-/* sub_magnitudes() subtracts the magnitudes of *x & *y assuming that */
-/* abs(*x) > abs(*y) > 0. */
-/* The sign of the difference *z is undefined. x&y may overlap but not x&z */
-/* or y&z. One guard digit is used. The error is less than one ulp. */
-/* *x & *y are left unchanged. */
-
+/* Subtract the magnitudes of *X and *Y assuming that abs (*x) > abs (*y) > 0.
+ The sign of the difference *Z is not changed. X and Y may overlap but not X
+ and Z or Y and Z. One guard digit is used. The error is less than one
+ ULP. */
static void sub_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
long i,j,k;
@@ -336,11 +321,9 @@ static void sub_magnitudes(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
-
-/* Add two multiple precision numbers. Set *z = *x + *y. x&y may overlap */
-/* but not x&z or y&z. One guard digit is used. The error is less than */
-/* one ulp. *x & *y are left unchanged. */
-
+/* Add *X and *Y and store the result in *Z. X and Y may overlap, but not X
+ and Z or Y and Z. One guard digit is used. The error is less than one
+ ULP. */
void __add(const mp_no *x, const mp_no *y, mp_no *z, int p) {
int n;
@@ -360,11 +343,9 @@ void __add(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
-
-/* Subtract two multiple precision numbers. *z is set to *x - *y. x&y may */
-/* overlap but not x&z or y&z. One guard digit is used. The error is */
-/* less than one ulp. *x & *y are left unchanged. */
-
+/* Subtract *Y from *X and return the result in *Z. X and Y may overlap but
+ not X and Z or Y and Z. One guard digit is used. The error is less than
+ one ULP. */
void __sub(const mp_no *x, const mp_no *y, mp_no *z, int p) {
int n;
@@ -384,12 +365,9 @@ void __sub(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
-
-/* Multiply two multiple precision numbers. *z is set to *x * *y. x&y */
-/* may overlap but not x&z or y&z. In case p=1,2,3 the exact result is */
-/* truncated to p digits. In case p>3 the error is bounded by 1.001 ulp. */
-/* *x & *y are left unchanged. */
-
+/* Multiply *X and *Y and store result in *Z. X and Y may overlap but not X
+ and Z or Y and Z. For P in [1, 2, 3], the exact result is truncated to P
+ digits. In case P > 3 the error is bounded by 1.001 ULP. */
void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
long i, i1, i2, j, k, k2;
@@ -407,12 +385,12 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
if (k > p2) {i1=k-p2; i2=p2+1; }
else {i1=1; i2=k; }
#if 1
- /* rearange this inner loop to allow the fmadd instructions to be
+ /* Rearrange this inner loop to allow the fmadd instructions to be
independent and execute in parallel on processors that have
dual symetrical FP pipelines. */
if (i1 < (i2-1))
{
- /* make sure we have at least 2 iterations */
+ /* Make sure we have at least 2 iterations. */
if (((i2 - i1) & 1L) == 1L)
{
/* Handle the odd iterations case. */
@@ -427,7 +405,7 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
zk += x->d[i]*y->d[j];
zk2 += x->d[i+1]*y->d[j-1];
}
- zk += zk2; /* final sum. */
+ zk += zk2; /* Final sum. */
}
else
{
@@ -447,7 +425,7 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
}
Z[k] = zk;
- /* Is there a carry beyond the most significant digit? */
+ /* Is there a carry beyond the most significant digit? */
if (Z[1] == ZERO) {
for (i=1; i<=p2; i++) Z[i]=Z[i+1];
EZ = EX + EY - 1; }
@@ -458,12 +436,12 @@ void __mul(const mp_no *x, const mp_no *y, mp_no *z, int p) {
return;
}
+/* Invert *X and store in *Y. Relative error bound:
+ - For P = 2: 1.001 * R ^ (1 - P)
+ - For P = 3: 1.063 * R ^ (1 - P)
+ - For P > 3: 2.001 * R ^ (1 - P)
-/* Invert a multiple precision number. Set *y = 1 / *x. */
-/* Relative error bound = 1.001*r**(1-p) for p=2, 1.063*r**(1-p) for p=3, */
-/* 2.001*r**(1-p) for p>3. */
-/* *x=0 is not permissible. *x is left unchanged. */
-
+ *X = 0 is not permissible. */
void __inv(const mp_no *x, mp_no *y, int p) {
long i;
double t;
@@ -487,12 +465,13 @@ void __inv(const mp_no *x, mp_no *y, int p) {
return;
}
+/* Divide *X by *Y and store result in *Z. X and Y may overlap but not X and Z
+ or Y and Z. Relative error bound:
+ - For P = 2: 2.001 * R ^ (1 - P)
+ - For P = 3: 2.063 * R ^ (1 - P)
+ - For P > 3: 3.001 * R ^ (1 - P)
-/* Divide one multiple precision number by another.Set *z = *x / *y. *x & *y */
-/* are left unchanged. x&y may overlap but not x&z or y&z. */
-/* Relative error bound = 2.001*r**(1-p) for p=2, 2.063*r**(1-p) for p=3 */
-/* and 3.001*r**(1-p) for p>3. *y=0 is not permissible. */
-
+ *X = 0 is not permissible. */
void __dvd(const mp_no *x, const mp_no *y, mp_no *z, int p) {
mp_no w;