qzdoom/src/m_fixed.h
alexey.lysiuk 25d53ecd2c Enabled position independent executable for generic GCC/Clang
This affects mostly Linux (and probably MinGW) as default toolchains for Windows and macOS have the corresponding option turned on by default
2017-12-29 09:39:01 +02:00

128 lines
4 KiB
C

#ifndef __M_FIXED__
#define __M_FIXED__
#include <stdlib.h>
#include "doomtype.h"
// Unfortunately, the Scale function still gets badly handled on 32 bit x86 platforms so it's the last remaining piece of inline assembly
// GCC inlines
#if defined(__GNUC__) && defined(__i386__) && !defined(__clang__) && !defined(__PIC__)
#ifndef alloca
// MinGW does not seem to come with alloca defined.
#define alloca __builtin_alloca
#endif
static inline int32_t Scale(int32_t a, int32_t b, int32_t c)
{
int32_t result, dummy;
asm volatile
("imull %3\n\t"
"idivl %4"
: "=a,a,a,a,a,a" (result),
"=&d,&d,&d,&d,d,d" (dummy)
: "a,a,a,a,a,a" (a),
"m,r,m,r,d,d" (b),
"r,r,m,m,r,m" (c)
: "cc"
);
return result;
}
// MSVC inlines
#elif defined(_MSC_VER) && defined(_M_IX86)
#pragma warning (disable: 4035)
__forceinline int32_t Scale(int32_t a, int32_t b, int32_t c)
{
__asm mov eax, a
__asm imul b
__asm idiv c
}
#pragma warning (default: 4035)
#else
static __forceinline int32_t Scale(int32_t a, int32_t b, int32_t c)
{
return (int32_t)(((int64_t)a*b) / c);
}
#endif
// Modern compilers are smart enough to do these multiplications intelligently.
__forceinline int32_t MulScale14(int32_t a, int32_t b) { return (int32_t)(((int64_t)a * b) >> 14); } // only used by R_DrawVoxel
__forceinline int32_t MulScale30(int32_t a, int32_t b) { return (int32_t)(((int64_t)a * b) >> 30); } // only used once in the node builder
__forceinline int32_t MulScale32(int32_t a, int32_t b) { return (int32_t)(((int64_t)a * b) >> 32); } // only used by R_DrawVoxel
__forceinline uint32_t UMulScale16(uint32_t a, uint32_t b) { return (uint32_t)(((uint64_t)a * b) >> 16); } // used for sky drawing
__forceinline int32_t DMulScale3(int32_t a, int32_t b, int32_t c, int32_t d) { return (int32_t)(((int64_t)a*b + (int64_t)c*d) >> 3); } // used for setting up slopes for Build maps
__forceinline int32_t DMulScale6(int32_t a, int32_t b, int32_t c, int32_t d) { return (int32_t)(((int64_t)a*b + (int64_t)c*d) >> 6); } // only used by R_DrawVoxel
__forceinline int32_t DMulScale10(int32_t a, int32_t b, int32_t c, int32_t d) { return (int32_t)(((int64_t)a*b + (int64_t)c*d) >> 10); } // only used by R_DrawVoxel
__forceinline int32_t DMulScale18(int32_t a, int32_t b, int32_t c, int32_t d) { return (int32_t)(((int64_t)a*b + (int64_t)c*d) >> 18); } // only used by R_DrawVoxel
__forceinline int32_t DMulScale32(int32_t a, int32_t b, int32_t c, int32_t d) { return (int32_t)(((int64_t)a*b + (int64_t)c*d) >> 32); } // used by R_PointOnSide.
// Sadly, for divisions this is not true but these are so infrequently used that the C versions are just fine, despite not being fully optimal.
__forceinline int32_t DivScale6(int32_t a, int32_t b) { return (int32_t)(((int64_t)a << 6) / b); } // only used by R_DrawVoxel
__forceinline int32_t DivScale21(int32_t a, int32_t b) { return (int32_t)(((int64_t)a << 21) / b); } // only used by R_DrawVoxel
__forceinline int32_t DivScale30(int32_t a, int32_t b) { return (int32_t)(((int64_t)a << 30) / b); } // only used once in the node builder
__forceinline void fillshort(void *buff, unsigned int count, uint16_t clear)
{
int16_t *b2 = (int16_t *)buff;
for (unsigned int i = 0; i != count; ++i)
{
b2[i] = clear;
}
}
#include "xs_Float.h"
inline int32_t FixedDiv (int32_t a, int32_t b)
{
if ((uint32_t)abs(a) >> (31-16) >= (uint32_t)abs (b))
return (a^b)<0 ? FIXED_MIN : FIXED_MAX;
return (int32_t)(((int64_t)a << 16) / b);
}
__forceinline int32_t FixedMul(int32_t a, int32_t b)
{
return (int32_t)(((int64_t)a * b) >> 16);
}
inline fixed_t FloatToFixed(double f)
{
return xs_Fix<16>::ToFix(f);
}
inline double FixedToFloat(fixed_t f)
{
return f / 65536.;
}
inline unsigned FloatToAngle(double f)
{
return xs_CRoundToInt((f)* (0x40000000 / 90.));
}
inline double AngleToFloat(unsigned f)
{
return f * (90. / 0x40000000);
}
inline double AngleToFloat(int f)
{
return f * (90. / 0x40000000);
}
#define FLOAT2FIXED(f) FloatToFixed(f)
#define FIXED2FLOAT(f) float(FixedToFloat(f))
#define FIXED2DBL(f) FixedToFloat(f)
#define ANGLE2DBL(f) AngleToFloat(f)
#endif