diff options
Diffstat (limited to 'mesalib/src/mesa/main/imports.c')
| -rw-r--r-- | mesalib/src/mesa/main/imports.c | 222 |
1 files changed, 1 insertions, 221 deletions
diff --git a/mesalib/src/mesa/main/imports.c b/mesalib/src/mesa/main/imports.c index 2d592a68e..0d6b56a51 100644 --- a/mesalib/src/mesa/main/imports.c +++ b/mesalib/src/mesa/main/imports.c @@ -223,19 +223,6 @@ _mesa_realloc(void *oldBuffer, size_t oldSize, size_t newSize) return newBuffer; } -/** - * 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; -} - /*@}*/ @@ -243,213 +230,6 @@ _mesa_memset16( unsigned short *dst, unsigned short val, size_t n ) /** \name Math */ /*@{*/ -/** Wrapper around sqrt() */ -double -_mesa_sqrtd(double x) -{ - return sqrt(x); -} - - -/* - * 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 */ - -void -_mesa_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 - fi_type 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 -#else - return (float) (1.0 / sqrt(n)); -#endif -} #ifndef __GNUC__ /** @@ -762,7 +542,7 @@ float _mesa_strtof( const char *s, char **end ) { #if defined(_GNU_SOURCE) && !defined(__CYGWIN__) && !defined(__FreeBSD__) && \ - !defined(ANDROID) && !defined(__HAIKU__) + !defined(ANDROID) && !defined(__HAIKU__) && !defined(__UCLIBC__) static locale_t loc = NULL; if (!loc) { loc = newlocale(LC_CTYPE_MASK, "C", NULL); |