Module Name: src
Committed By: riastradh
Date: Wed Jul 17 12:00:13 UTC 2024
Modified Files:
src/lib/libm/src: math_private.h
Log Message:
libm/src/math_private.h: Tidy up comments and whitespace.
Clarify which words are which when ambiguous.
Say `significand', not `mantissa'; we're not talking about books of
log tables here. (Strictly speaking, this may refer either to what
IEEE 754 calls the trailing significand field of the binary encoding,
which is a sequence of bits rather than a real number in [1,2), or,
for ld80 with an explicit 1-bit, what might be called the significand
field since it's not just the trailing part after the dot. But the
term `significand' will serve as a proxy for these cases.)
To generate a diff of this commit:
cvs rdiff -u -r1.33 -r1.34 src/lib/libm/src/math_private.h
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/lib/libm/src/math_private.h
diff -u src/lib/libm/src/math_private.h:1.33 src/lib/libm/src/math_private.h:1.34
--- src/lib/libm/src/math_private.h:1.33 Wed Jul 17 11:59:58 2024
+++ src/lib/libm/src/math_private.h Wed Jul 17 12:00:13 2024
@@ -11,7 +11,7 @@
/*
* from: @(#)fdlibm.h 5.1 93/09/24
- * $NetBSD: math_private.h,v 1.33 2024/07/17 11:59:58 riastradh Exp $
+ * $NetBSD: math_private.h,v 1.34 2024/07/17 12:00:13 riastradh Exp $
*/
#ifndef _MATH_PRIVATE_H_
@@ -20,23 +20,18 @@
#include <assert.h>
#include <sys/types.h>
-/* The original fdlibm code used statements like:
- n0 = ((*(int*)&one)>>29)^1; * index of high word *
- ix0 = *(n0+(int*)&x); * high word of x *
- ix1 = *((1-n0)+(int*)&x); * low word of x *
- to dig two 32 bit words out of the 64 bit IEEE floating point
- value. That is non-ANSI, and, moreover, the gcc instruction
- scheduler gets it wrong. We instead use the following macros.
- Unlike the original code, we determine the endianness at compile
- time, not at run time; I don't see much benefit to selecting
- endianness at run time. */
-
-/* A union which permits us to convert between a double and two 32 bit
- ints. */
-
/*
- * A union which permits us to convert between a double and two 32 bit
- * ints.
+ * The original fdlibm code used statements like:
+ *
+ * n0 = ((*(int*)&one)>>29)^1; // index of high word
+ * ix0 = *(n0+(int*)&x); // high word of x
+ * ix1 = *((1-n0)+(int*)&x); // low word of x
+ *
+ * to dig two 32-bit words out of the-64 bit IEEE floating point value.
+ * That is non-ANSI, and, moreover, the gcc instruction scheduler gets
+ * it wrong. We instead use the following macros. Unlike the original
+ * code, we determine the endianness at compile time, not at run time;
+ * I don't see much benefit to selecting endianness at run time.
*/
#ifdef __arm__
@@ -49,8 +44,10 @@
#define IEEE_WORD_ORDER BYTE_ORDER
#endif
-/* A union which permits us to convert between a long double and
- four 32 bit ints. */
+/*
+ * A union which permits us to convert between a long double and
+ * four 32-bit integers.
+ */
#if IEEE_WORD_ORDER == BIG_ENDIAN
@@ -90,6 +87,11 @@ typedef union
#endif
+/*
+ * A union which permits us to convert between a double and two 32-bit
+ * integers.
+ */
+
#if IEEE_WORD_ORDER == BIG_ENDIAN
typedef union
@@ -126,7 +128,7 @@ typedef union
#endif
-/* Get two 32 bit ints from a double. */
+/* Get two 32-bit integers from a double. */
#define EXTRACT_WORDS(ix0,ix1,d) \
do { \
@@ -136,7 +138,7 @@ do { \
(ix1) = ew_u.parts.lsw; \
} while (0)
-/* Get a 64-bit int from a double. */
+/* Get a 64-bit integer from a double. */
#define EXTRACT_WORD64(ix,d) \
do { \
ieee_double_shape_type ew_u; \
@@ -145,7 +147,7 @@ do { \
} while (0)
-/* Get the more significant 32 bit int from a double. */
+/* Get the more significant 32-bit integer from a double. */
#define GET_HIGH_WORD(i,d) \
do { \
@@ -154,7 +156,7 @@ do { \
(i) = gh_u.parts.msw; \
} while (0)
-/* Get the less significant 32 bit int from a double. */
+/* Get the less significant 32-bit integer from a double. */
#define GET_LOW_WORD(i,d) \
do { \
@@ -163,7 +165,7 @@ do { \
(i) = gl_u.parts.lsw; \
} while (0)
-/* Set a double from two 32 bit ints. */
+/* Set a double from two 32-bit integers. */
#define INSERT_WORDS(d,ix0,ix1) \
do { \
@@ -173,7 +175,8 @@ do { \
(d) = iw_u.value; \
} while (0)
-/* Set a double from a 64-bit int. */
+/* Set a double from a 64-bit integer. */
+
#define INSERT_WORD64(d,ix) \
do { \
ieee_double_shape_type iw_u; \
@@ -181,8 +184,7 @@ do { \
(d) = iw_u.value; \
} while (0)
-
-/* Set the more significant 32 bits of a double from an int. */
+/* Set the more significant 32 bits of a double from an integer. */
#define SET_HIGH_WORD(d,v) \
do { \
@@ -192,7 +194,7 @@ do { \
(d) = sh_u.value; \
} while (0)
-/* Set the less significant 32 bits of a double from an int. */
+/* Set the less significant 32 bits of a double from an integer. */
#define SET_LOW_WORD(d,v) \
do { \
@@ -202,8 +204,10 @@ do { \
(d) = sl_u.value; \
} while (0)
-/* A union which permits us to convert between a float and a 32 bit
- int. */
+/*
+ * A union which permits us to convert between a float and a 32-bit
+ * integer.
+ */
typedef union
{
@@ -211,7 +215,7 @@ typedef union
u_int32_t word;
} ieee_float_shape_type;
-/* Get a 32 bit int from a float. */
+/* Get a 32-bit integer from a float. */
#define GET_FLOAT_WORD(i,d) \
do { \
@@ -220,7 +224,7 @@ do { \
(i) = gf_u.word; \
} while (0)
-/* Set a float from a 32 bit int. */
+/* Set a float from a 32-bit integer. */
#define SET_FLOAT_WORD(d,i) \
do { \
@@ -240,10 +244,9 @@ do { \
((u)->extu_fracl = (v) & ((1ULL << EXT_FRACLBITS) - 1), \
(u)->extu_frach = (v) >> EXT_FRACLBITS)
-
/*
- * Get expsign and mantissa as 16 bit and 64 bit ints from an 80 bit long
- * double.
+ * Get expsign as 16-bit integer ix0 and significand as 64-bit integer
+ * ix1 from an 80-bit long double d.
*/
#define EXTRACT_LDBL80_WORDS(ix0,ix1,d) \
@@ -255,8 +258,9 @@ do { \
} while (0)
/*
- * Get expsign and mantissa as one 16 bit and two 64 bit ints from a 128 bit
- * long double.
+ * Get expsign as 16-bit integer ix0 and significand as two 64-bit
+ * integers, ix1 high-order and ix2 low-order, from a 128-bit long
+ * double d.
*/
#define EXTRACT_LDBL128_WORDS(ix0,ix1,ix2,d) \
@@ -268,7 +272,7 @@ do { \
(ix2) = ew_u.extu_fracl; \
} while (0)
-/* Get expsign as a 16 bit int from a long double. */
+/* Get expsign as a 16-bit integer i from a long double d. */
#define GET_LDBL_EXPSIGN(i,d) \
do { \
@@ -278,8 +282,8 @@ do { \
} while (0)
/*
- * Set an 80 bit long double from a 16 bit int expsign and a 64 bit int
- * mantissa.
+ * Set an 80-bit long double d from a 16-bit integer expsign ix0 and a
+ * 64-bit integer significand ix1.
*/
#define INSERT_LDBL80_WORDS(d,ix0,ix1) \
@@ -291,8 +295,9 @@ do { \
} while (0)
/*
- * Set a 128 bit long double from a 16 bit int expsign and two 64 bit ints
- * comprising the mantissa.
+ * Set a 128-bit long double d from a 16-bit integer expsign ix0 and
+ * two 64-bit integers composing the significand, ix1 high-order and
+ * ix2 low-order.
*/
#define INSERT_LDBL128_WORDS(d,ix0,ix1,ix2) \
@@ -304,7 +309,7 @@ do { \
(d) = iw_u.extu_ld; \
} while (0)
-/* Set expsign of a long double from a 16 bit int. */
+/* Set expsign of a long double from a 16-bit integer. */
#define SET_LDBL_EXPSIGN(d,v) \
do { \
@@ -503,7 +508,7 @@ void _scan_nan(uint32_t *__words, int __
*
* When one arg is NaN, the result is typically that arg quieted. When both
* args are NaNs, the result is typically the quietening of the arg whose
- * mantissa is largest after quietening. When neither arg is NaN, the
+ * significand is largest after quietening. When neither arg is NaN, the
* result may be NaN because it is indeterminate, or finite for subsequent
* construction of a NaN as the indeterminate 0.0L/0.0L.
*
@@ -680,7 +685,7 @@ extern long double __ieee754_fmodl(long
extern long double __ieee754_sqrtl(long double);
/*
- * TRUNC() is a macro that sets the trailing 27 bits in the mantissa of an
+ * TRUNC() is a macro that sets the trailing 27 bits in the significand of an
* IEEE double variable to zero. It must be expression-like for syntactic
* reasons, and we implement this expression using an inline function
* instead of a pure macro to avoid depending on the gcc feature of
@@ -876,10 +881,10 @@ irintl(long double x)
#define breakpoint() asm("int $3")
#else
#include <signal.h>
-
+
#define breakpoint() raise(SIGTRAP)
-#endif
-#endif
+#endif
+#endif
#ifdef STRUCT_RETURN
#define RETURNSP(rp) do { \
