OpenLibm working on 16-bit 8086

Hello all,

I'm not sure whether anyone is interested in this, but I have successfully ported a number of the OpenLibm math routines to [ELKS](https://github.com/jbruchon/elks), an 8086-based Linux kernel and C library, using the [ia16-elf-gcc](https://github.com/tkchia/gcc-ia16) compiler. In this system, `int` is 16 bits, and `long` 32 bits. `float` and `double` are IEEE 754 32 and 64 bits.

The following patch was required. It may (or may not) be a good idea to consider changing the non-portable `unsigned int` definitions to something like `uint32_t` for portability. Not knowing this library well, I am unsure whether `unsigned int` may need to be 64 bits on some systems, in which case, this would not work. However, it seems the IEEEf2bits structure assumes unsigned int to be 32 bits for its bitfield definitions.
```
diff --git a/src/fpmath.h b/src/fpmath.h
index 6c37595..5843386 100644
--- a/src/fpmath.h
+++ b/src/fpmath.h
@@ -83,13 +83,13 @@ union IEEEf2bits {
float f;
struct {
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
- unsigned int man :23;
- unsigned int exp :8;
- unsigned int sign :1;
+ unsigned long man :23;
+ unsigned long exp :8;
+ unsigned long sign :1;
#else /* _BIG_ENDIAN */
- unsigned int sign :1;
- unsigned int exp :8;
- unsigned int man :23;
+ unsigned long sign :1;
+ unsigned long exp :8;
+ unsigned long man :23;
#endif
} bits;
};
@@ -102,19 +102,19 @@ union IEEEd2bits {
struct {
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#if __FLOAT_WORD_ORDER__ == __ORDER_LITTLE_ENDIAN__
- unsigned int manl :32;
+ unsigned long manl :32;
#endif
- unsigned int manh :20;
- unsigned int exp :11;
- unsigned int sign :1;
+ unsigned long manh :20;
+ unsigned long exp :11;
+ unsigned long sign :1;
#if __FLOAT_WORD_ORDER__ == __ORDER_BIG_ENDIAN__
- unsigned int manl :32;
+ unsigned long manl :32;
#endif
#else /* _BIG_ENDIAN */
- unsigned int sign :1;
- unsigned int exp :11;
- unsigned int manh :20;
- unsigned int manl :32;
+ unsigned long sign :1;
+ unsigned long exp :11;
+ unsigned long manh :20;
+ unsigned long manl :32;
#endif
} bits;
};
diff --git a/src/i386_fpmath.h b/src/i386_fpmath.h
index 455631c..8b29e38 100644
--- a/src/i386_fpmath.h
+++ b/src/i386_fpmath.h
@@ -29,16 +29,16 @@
union IEEEl2bits {
long double e;
struct {
- unsigned int manl :32;
- unsigned int manh :32;
- unsigned int exp :15;
- unsigned int sign :1;
- unsigned int junk :16;
+ unsigned long manl :32;
+ unsigned long manh :32;
+ unsigned long exp :15;
+ unsigned long sign :1;
+ unsigned long junk :16;
} bits;
struct {
unsigned long long man :64;
- unsigned int expsign :16;
- unsigned int junk :16;
+ unsigned long expsign :16;
+ unsigned long junk :16;
} xbits;
};

diff --git a/src/math_private.h b/src/math_private.h
index 15a27b2..4f7e1d4 100644
--- a/src/math_private.h
+++ b/src/math_private.h
@@ -162,7 +162,7 @@ typedef union
{
float value;
/* FIXME: Assumes 32 bit int. */
- unsigned int word;
+ unsigned long word;
} ieee_float_shape_type;

/* Get a 32 bit int from a float. */
```

Thank you!