📄 imports.c
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/**
* \file imports.c
* Standard C library function wrappers.
*
* Imports are services which the device driver or window system or
* operating system provides to the core renderer. The core renderer (Mesa)
* will call these functions in order to do memory allocation, simple I/O,
* etc.
*
* Some drivers will want to override/replace this file with something
* specialized, but that'll be rare.
*
* Eventually, I want to move roll the glheader.h file into this.
*
* The OpenGL SI's __GLimports structure allows per-context specification of
* replacements for the standard C lib functions. In practice that's probably
* never needed; compile-time replacements are far more likely.
*
* The _mesa_*() functions defined here don't in general take a context
* parameter. I guess we can change that someday, if need be.
* So for now, the __GLimports stuff really isn't used.
*
* \todo Functions still needed:
* - scanf
* - qsort
* - bsearch
* - rand and RAND_MAX
*
* \note When compiled into a XFree86 module these functions wrap around
* XFree86 own wrappers.
*/
/*
* Mesa 3-D graphics library
* Version: 6.3
*
* Copyright (C) 1999-2005 Brian Paul All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the "Software"),
* to deal in the Software without restriction, including without limitation
* the rights to use, copy, modify, merge, publish, distribute, sublicense,
* and/or sell copies of the Software, and to permit persons to whom the
* Software is furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included
* in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
* AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*/
#include "imports.h"
#include "context.h"
#include "version.h"
#define MAXSTRING 4000 /* for vsnprintf() */
#ifdef WIN32
#define vsnprintf _vsnprintf
#elif defined(__IBMC__) || defined(__IBMCPP__) || ( defined(__VMS) && __CRTL_VER < 70312000 )
extern int vsnprintf(char *str, size_t count, const char *fmt, va_list arg);
#ifdef __VMS
#include "vsnprintf.c"
#endif
#endif
/**********************************************************************/
/** \name Memory */
/*@{*/
/** Wrapper around either malloc() or xf86malloc() */
void *
_mesa_malloc(size_t bytes)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
return xf86malloc(bytes);
#else
return malloc(bytes);
#endif
}
/** Wrapper around either calloc() or xf86calloc() */
void *
_mesa_calloc(size_t bytes)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
return xf86calloc(1, bytes);
#else
return calloc(1, bytes);
#endif
}
/** Wrapper around either free() or xf86free() */
void
_mesa_free(void *ptr)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
xf86free(ptr);
#else
free(ptr);
#endif
}
/**
* Allocate aligned memory.
*
* \param bytes number of bytes to allocate.
* \param alignment alignment (must be greater than zero).
*
* Allocates extra memory to accommodate rounding up the address for
* alignment and to record the real malloc address.
*
* \sa _mesa_align_free().
*/
void *
_mesa_align_malloc(size_t bytes, unsigned long alignment)
{
uintptr_t ptr, buf;
ASSERT( alignment > 0 );
ptr = (uintptr_t) _mesa_malloc(bytes + alignment + sizeof(void *));
if (!ptr)
return NULL;
buf = (ptr + alignment + sizeof(void *)) & ~(uintptr_t)(alignment - 1);
*(uintptr_t *)(buf - sizeof(void *)) = ptr;
#ifdef DEBUG
/* mark the non-aligned area */
while ( ptr < buf - sizeof(void *) ) {
*(unsigned long *)ptr = 0xcdcdcdcd;
ptr += sizeof(unsigned long);
}
#endif
return (void *) buf;
}
/**
* Same as _mesa_align_malloc(), but using _mesa_calloc() instead of
* _mesa_malloc()
*/
void *
_mesa_align_calloc(size_t bytes, unsigned long alignment)
{
uintptr_t ptr, buf;
ASSERT( alignment > 0 );
ptr = (uintptr_t) _mesa_calloc(bytes + alignment + sizeof(void *));
if (!ptr)
return NULL;
buf = (ptr + alignment + sizeof(void *)) & ~(uintptr_t)(alignment - 1);
*(uintptr_t *)(buf - sizeof(void *)) = ptr;
#ifdef DEBUG
/* mark the non-aligned area */
while ( ptr < buf - sizeof(void *) ) {
*(unsigned long *)ptr = 0xcdcdcdcd;
ptr += sizeof(unsigned long);
}
#endif
return (void *)buf;
}
/**
* Free memory which was allocated with either _mesa_align_malloc()
* or _mesa_align_calloc().
* \param ptr pointer to the memory to be freed.
* The actual address to free is stored in the word immediately before the
* address the client sees.
*/
void
_mesa_align_free(void *ptr)
{
#if 0
_mesa_free( (void *)(*(unsigned long *)((unsigned long)ptr - sizeof(void *))) );
#else
void **cubbyHole = (void **) ((char *) ptr - sizeof(void *));
void *realAddr = *cubbyHole;
_mesa_free(realAddr);
#endif
}
/** Reallocate memory */
void *
_mesa_realloc(void *oldBuffer, size_t oldSize, size_t newSize)
{
const size_t copySize = (oldSize < newSize) ? oldSize : newSize;
void *newBuffer = _mesa_malloc(newSize);
if (newBuffer && oldBuffer && copySize > 0)
_mesa_memcpy(newBuffer, oldBuffer, copySize);
if (oldBuffer)
_mesa_free(oldBuffer);
return newBuffer;
}
/** memcpy wrapper */
void *
_mesa_memcpy(void *dest, const void *src, size_t n)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
return xf86memcpy(dest, src, n);
#elif defined(SUNOS4)
return memcpy((char *) dest, (char *) src, (int) n);
#else
return memcpy(dest, src, n);
#endif
}
/** Wrapper around either memset() or xf86memset() */
void
_mesa_memset( void *dst, int val, size_t n )
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
xf86memset( dst, val, n );
#elif defined(SUNOS4)
memset( (char *) dst, (int) val, (int) n );
#else
memset(dst, val, n);
#endif
}
/**
* Fill memory with a constant 16bit word.
* \param dst destination pointer.
* \param val value.
* \param n number of words.
*/
void
_mesa_memset16( unsigned short *dst, unsigned short val, size_t n )
{
while (n-- > 0)
*dst++ = val;
}
/** Wrapper around either memcpy() or xf86memcpy() or bzero() */
void
_mesa_bzero( void *dst, size_t n )
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
xf86memset( dst, 0, n );
#elif defined(__FreeBSD__)
bzero( dst, n );
#else
memset( dst, 0, n );
#endif
}
/*@}*/
/**********************************************************************/
/** \name Math */
/*@{*/
/** Wrapper around either sin() or xf86sin() */
double
_mesa_sin(double a)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
return xf86sin(a);
#else
return sin(a);
#endif
}
/** Wrapper around either cos() or xf86cos() */
double
_mesa_cos(double a)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
return xf86cos(a);
#else
return cos(a);
#endif
}
/** Wrapper around either sqrt() or xf86sqrt() */
double
_mesa_sqrtd(double x)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
return xf86sqrt(x);
#else
return sqrt(x);
#endif
}
/*
* A High Speed, Low Precision Square Root
* by Paul Lalonde and Robert Dawson
* from "Graphics Gems", Academic Press, 1990
*
* SPARC implementation of a fast square root by table
* lookup.
* SPARC floating point format is as follows:
*
* BIT 31 30 23 22 0
* sign exponent mantissa
*/
static short sqrttab[0x100]; /* declare table of square roots */
static void init_sqrt_table(void)
{
#if defined(USE_IEEE) && !defined(DEBUG)
unsigned short i;
fi_type fi; /* to access the bits of a float in C quickly */
/* we use a union defined in glheader.h */
for(i=0; i<= 0x7f; i++) {
fi.i = 0;
/*
* Build a float with the bit pattern i as mantissa
* and an exponent of 0, stored as 127
*/
fi.i = (i << 16) | (127 << 23);
fi.f = _mesa_sqrtd(fi.f);
/*
* Take the square root then strip the first 7 bits of
* the mantissa into the table
*/
sqrttab[i] = (fi.i & 0x7fffff) >> 16;
/*
* Repeat the process, this time with an exponent of
* 1, stored as 128
*/
fi.i = 0;
fi.i = (i << 16) | (128 << 23);
fi.f = sqrt(fi.f);
sqrttab[i+0x80] = (fi.i & 0x7fffff) >> 16;
}
#else
(void) sqrttab; /* silence compiler warnings */
#endif /*HAVE_FAST_MATH*/
}
/**
* Single precision square root.
*/
float
_mesa_sqrtf( float x )
{
#if defined(USE_IEEE) && !defined(DEBUG)
fi_type num;
/* to access the bits of a float in C
* we use a union from glheader.h */
short e; /* the exponent */
if (x == 0.0F) return 0.0F; /* check for square root of 0 */
num.f = x;
e = (num.i >> 23) - 127; /* get the exponent - on a SPARC the */
/* exponent is stored with 127 added */
num.i &= 0x7fffff; /* leave only the mantissa */
if (e & 0x01) num.i |= 0x800000;
/* the exponent is odd so we have to */
/* look it up in the second half of */
/* the lookup table, so we set the */
/* high bit */
e >>= 1; /* divide the exponent by two */
/* note that in C the shift */
/* operators are sign preserving */
/* for signed operands */
/* Do the table lookup, based on the quaternary mantissa,
* then reconstruct the result back into a float
*/
num.i = ((sqrttab[num.i >> 16]) << 16) | ((e + 127) << 23);
return num.f;
#else
return (float) _mesa_sqrtd((double) x);
#endif
}
/**
inv_sqrt - A single precision 1/sqrt routine for IEEE format floats.
written by Josh Vanderhoof, based on newsgroup posts by James Van Buskirk
and Vesa Karvonen.
*/
float
_mesa_inv_sqrtf(float n)
{
#if defined(USE_IEEE) && !defined(DEBUG)
float r0, x0, y0;
float r1, x1, y1;
float r2, x2, y2;
#if 0 /* not used, see below -BP */
float r3, x3, y3;
#endif
union { float f; unsigned int i; } u;
unsigned int magic;
/*
Exponent part of the magic number -
We want to:
1. subtract the bias from the exponent,
2. negate it
3. divide by two (rounding towards -inf)
4. add the bias back
Which is the same as subtracting the exponent from 381 and dividing
by 2.
floor(-(x - 127) / 2) + 127 = floor((381 - x) / 2)
*/
magic = 381 << 23;
/*
Significand part of magic number -
With the current magic number, "(magic - u.i) >> 1" will give you:
for 1 <= u.f <= 2: 1.25 - u.f / 4
for 2 <= u.f <= 4: 1.00 - u.f / 8
This isn't a bad approximation of 1/sqrt. The maximum difference from
1/sqrt will be around .06. After three Newton-Raphson iterations, the
maximum difference is less than 4.5e-8. (Which is actually close
enough to make the following bias academic...)
To get a better approximation you can add a bias to the magic
number. For example, if you subtract 1/2 of the maximum difference in
the first approximation (.03), you will get the following function:
for 1 <= u.f <= 2: 1.22 - u.f / 4
for 2 <= u.f <= 3.76: 0.97 - u.f / 8
for 3.76 <= u.f <= 4: 0.72 - u.f / 16
(The 3.76 to 4 range is where the result is < .5.)
This is the closest possible initial approximation, but with a maximum
error of 8e-11 after three NR iterations, it is still not perfect. If
you subtract 0.0332281 instead of .03, the maximum error will be
2.5e-11 after three NR iterations, which should be about as close as
is possible.
for 1 <= u.f <= 2: 1.2167719 - u.f / 4
for 2 <= u.f <= 3.73: 0.9667719 - u.f / 8
for 3.73 <= u.f <= 4: 0.7167719 - u.f / 16
*/
magic -= (int)(0.0332281 * (1 << 25));
u.f = n;
u.i = (magic - u.i) >> 1;
/*
Instead of Newton-Raphson, we use Goldschmidt's algorithm, which
allows more parallelism. From what I understand, the parallelism
comes at the cost of less precision, because it lets error
accumulate across iterations.
*/
x0 = 1.0f;
y0 = 0.5f * n;
r0 = u.f;
x1 = x0 * r0;
y1 = y0 * r0 * r0;
r1 = 1.5f - y1;
x2 = x1 * r1;
y2 = y1 * r1 * r1;
r2 = 1.5f - y2;
#if 1
return x2 * r2; /* we can stop here, and be conformant -BP */
#else
x3 = x2 * r2;
y3 = y2 * r2 * r2;
r3 = 1.5f - y3;
return x3 * r3;
#endif
#elif defined(XFree86LOADER) && defined(IN_MODULE)
return 1.0F / xf86sqrt(n);
#else
return (float) (1.0 / sqrt(n));
#endif
}
/**
* Wrapper around either pow() or xf86pow().
*/
double
_mesa_pow(double x, double y)
{
#if defined(XFree86LOADER) && defined(IN_MODULE)
return xf86pow(x, y);
#else
return pow(x, y);
#endif
}
/**
* Return number of bits set in given GLuint.
*/
unsigned int
_mesa_bitcount(unsigned int n)
{
unsigned int bits;
for (bits = 0; n > 0; n = n >> 1) {
bits += (n & 1);
}
return bits;
}
/**
* Convert a 4-byte float to a 2-byte half float.
* Based on code from:
* http://www.opengl.org/discussion_boards/ubb/Forum3/HTML/008786.html
*/
GLhalfARB
_mesa_float_to_half(float val)
{
const int flt = *((int *) (void *) &val);
const int flt_m = flt & 0x7fffff;
const int flt_e = (flt >> 23) & 0xff;
const int flt_s = (flt >> 31) & 0x1;
int s, e, m = 0;
GLhalfARB result;
/* sign bit */
s = flt_s;
/* handle special cases */
if ((flt_e == 0) && (flt_m == 0)) {
/* zero */
/* m = 0; - already set */
e = 0;
}
else if ((flt_e == 0) && (flt_m != 0)) {
/* denorm -- denorm float maps to 0 half */
/* m = 0; - already set */
e = 0;
}
else if ((flt_e == 0xff) && (flt_m == 0)) {
/* infinity */
/* m = 0; - already set */
e = 31;
}
else if ((flt_e == 0xff) && (flt_m != 0)) {
/* NaN */
m = 1;
e = 31;
}
else {
/* regular number */
const int new_exp = flt_e - 127;
if (new_exp < -24) {
/* this maps to 0 */
/* m = 0; - already set */
e = 0;
}
else if (new_exp < -14) {
/* this maps to a denorm */
unsigned int exp_val = (unsigned int) (-14 - new_exp); /* 2^-exp_val*/
e = 0;
switch (exp_val) {
case 0:
_mesa_warning(NULL,
"float_to_half: logical error in denorm creation!\n");
/* m = 0; - already set */
break;
case 1: m = 512 + (flt_m >> 14); break;
case 2: m = 256 + (flt_m >> 15); break;
case 3: m = 128 + (flt_m >> 16); break;
case 4: m = 64 + (flt_m >> 17); break;
case 5: m = 32 + (flt_m >> 18); break;
case 6: m = 16 + (flt_m >> 19); break;
case 7: m = 8 + (flt_m >> 20); break;
case 8: m = 4 + (flt_m >> 21); break;
case 9: m = 2 + (flt_m >> 22); break;
case 10: m = 1; break;
}
}
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