bugfix: 修复浮点数打印错误的bug

kernel/common/math/Makefile

@@ -0,0 +1,14 @@
+
+
+CFLAGS += -I .
+
+all: fabs.o round.o pow.o
+
+fabs.o: fabs.c
+	gcc $(CFLAGS) -c fabs.c -o fabs.o
+
+round.o: round.c
+	gcc $(CFLAGS) -c round.c -o round.o
+
+pow.o: pow.c
+	gcc $(CFLAGS) -c pow.c -o pow.o

kernel/common/math/fabs.c

@@ -0,0 +1,30 @@
+#include <common/math.h>
+#include <common/sys/types.h>
+#include "libm.h"
+
+double fabs(double x)
+{
+    union
+    {
+        double f;
+        uint64_t i;
+    } u = {x};
+    u.i &= -1ULL / 2;
+    return u.f;
+}
+
+
+#if __LDBL_MANT_DIG__ == 53 &&  __LDBL_MAX_EXP__ == 1024
+long double fabsl(long double x)
+{
+	return fabs(x);
+}
+#elif (__LDBL_MANT_DIG__ == 64 || __LDBL_MANT_DIG__ == 113) && __LDBL_MAX_EXP__ == 16384
+long double fabsl(long double x)
+{
+	union ldshape u = {x};
+
+	u.i.se &= 0x7fff;
+	return u.f;
+}
+#endif

kernel/common/math/libm.h

@@ -0,0 +1,75 @@
+#pragma once
+#include <common/sys/types.h>
+
+// ===== 描述long double 的数据比特结构
+#if __LDBL_MANT_DIG__ == 53 && __LDBL_MAX_EXP__ == 1024
+#elif __LDBL_MANT_DIG__ == 64 && __LDBL_MAX_EXP__ == 16384 && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+union ldshape
+{
+    long double f;
+    struct
+    {
+        uint64_t m;
+        uint16_t se;
+    } i;
+};
+#elif __LDBL_MANT_DIG__ == 113 && __LDBL_MAX_EXP__ == 16384 && __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+union ldshape
+{
+    long double f;
+    struct
+    {
+        uint64_t lo;
+        uint32_t mid;
+        uint16_t top;
+        uint16_t se;
+    } i;
+    struct
+    {
+        uint64_t lo;
+        uint64_t hi;
+    } i2;
+};
+#elif __LDBL_MANT_DIG__ == 113 && __LDBL_MAX_EXP__ == 16384 && __BYTE_ORDER__ == __BIG_ENDIAN
+union ldshape
+{
+    long double f;
+    struct
+    {
+        uint16_t se;
+        uint16_t top;
+        uint32_t mid;
+        uint64_t lo;
+    } i;
+    struct
+    {
+        uint64_t hi;
+        uint64_t lo;
+    } i2;
+};
+#else
+#error Unsupported long double representation
+#endif
+
+#define FORCE_EVAL(x)                         \
+    do                                        \
+    {                                         \
+        if (sizeof(x) == sizeof(float))       \
+        {                                     \
+            volatile float __x;               \
+            __x = (x);                        \
+            (void)__x;                        \
+        }                                     \
+        else if (sizeof(x) == sizeof(double)) \
+        {                                     \
+            volatile double __x;              \
+            __x = (x);                        \
+            (void)__x;                        \
+        }                                     \
+        else                                  \
+        {                                     \
+            volatile long double __x;         \
+            __x = (x);                        \
+            (void)__x;                        \
+        }                                     \
+    } while (0)

kernel/common/math/pow.c

@@ -0,0 +1,10 @@
+#include <common/math.h>
+#include <common/stddef.h>
+
+int64_t pow(int64_t x, int y)
+{
+    int64_t res = 1;
+    for (int i = 0; i < y; ++i)
+        res *= x;
+    return res;
+}

kernel/common/math/round.c

@@ -0,0 +1,43 @@
+
+
+#include "libm.h"
+
+#if __FLT_EVAL_METHOD__ == 0 || __FLT_EVAL_METHOD__ == 1
+#define EPS __DBL_EPSILON__
+#elif __FLT_EVAL_METHOD__ == 2
+#define EPS __LDBL_EPSILON__
+#endif
+static const double toint = 1 / EPS;
+
+double round(double x)
+{
+    union
+    {
+        double f;
+        uint64_t i;
+    } u = {x};
+    
+    int e = u.i >> 52 & 0x7ff;
+    double y;
+
+    if (e >= 0x3ff + 52)
+        return x;
+    if (u.i >> 63)
+        x = -x;
+    if (e < 0x3ff - 1)
+    {
+        /* raise inexact if x!=0 */
+        FORCE_EVAL(x + toint);
+        return 0 * u.f;
+    }
+    y = x + toint - toint - x;
+    if (y > 0.5)
+        y = y + x - 1;
+    else if (y <= -0.5)
+        y = y + x + 1;
+    else
+        y = y + x;
+    if (u.i >> 63)
+        y = -y;
+    return y;
+}