257 lines
11 KiB
C
257 lines
11 KiB
C
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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* Contains misc. useful macros & defines.
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* \file IceUtils.h
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* \author Pierre Terdiman (collected from various sources)
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* \date April, 4, 2000
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*/
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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// Include Guard
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#ifndef __ICEUTILS_H__
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#define __ICEUTILS_H__
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#define START_RUNONCE { static bool __RunOnce__ = false; if(!__RunOnce__){
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#define END_RUNONCE __RunOnce__ = true;}}
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//! Reverse all the bits in a 32 bit word (from Steve Baker's Cute Code Collection)
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//! (each line can be done in any order.
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inline_ void ReverseBits(udword& n)
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{
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n = ((n >> 1) & 0x55555555) | ((n << 1) & 0xaaaaaaaa);
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n = ((n >> 2) & 0x33333333) | ((n << 2) & 0xcccccccc);
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n = ((n >> 4) & 0x0f0f0f0f) | ((n << 4) & 0xf0f0f0f0);
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n = ((n >> 8) & 0x00ff00ff) | ((n << 8) & 0xff00ff00);
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n = ((n >> 16) & 0x0000ffff) | ((n << 16) & 0xffff0000);
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// Etc for larger intergers (64 bits in Java)
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// NOTE: the >> operation must be unsigned! (>>> in java)
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}
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//! Count the number of '1' bits in a 32 bit word (from Steve Baker's Cute Code Collection)
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inline_ udword CountBits(udword n)
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{
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// This relies of the fact that the count of n bits can NOT overflow
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// an n bit interger. EG: 1 bit count takes a 1 bit interger, 2 bit counts
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// 2 bit interger, 3 bit count requires only a 2 bit interger.
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// So we add all bit pairs, then each nible, then each byte etc...
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n = (n & 0x55555555) + ((n & 0xaaaaaaaa) >> 1);
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n = (n & 0x33333333) + ((n & 0xcccccccc) >> 2);
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n = (n & 0x0f0f0f0f) + ((n & 0xf0f0f0f0) >> 4);
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n = (n & 0x00ff00ff) + ((n & 0xff00ff00) >> 8);
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n = (n & 0x0000ffff) + ((n & 0xffff0000) >> 16);
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// Etc for larger intergers (64 bits in Java)
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// NOTE: the >> operation must be unsigned! (>>> in java)
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return n;
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}
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//! Even faster?
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inline_ udword CountBits2(udword bits)
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{
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bits = bits - ((bits >> 1) & 0x55555555);
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bits = ((bits >> 2) & 0x33333333) + (bits & 0x33333333);
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bits = ((bits >> 4) + bits) & 0x0F0F0F0F;
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return (bits * 0x01010101) >> 24;
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}
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//! Spread out bits. EG 00001111 -> 0101010101
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//! 00001010 -> 0100010000
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//! This is used to interleve to intergers to produce a `Morten Key'
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//! used in Space Filling Curves (See DrDobbs Journal, July 1999)
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//! Order is important.
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inline_ void SpreadBits(udword& n)
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{
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n = ( n & 0x0000ffff) | (( n & 0xffff0000) << 16);
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n = ( n & 0x000000ff) | (( n & 0x0000ff00) << 8);
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n = ( n & 0x000f000f) | (( n & 0x00f000f0) << 4);
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n = ( n & 0x03030303) | (( n & 0x0c0c0c0c) << 2);
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n = ( n & 0x11111111) | (( n & 0x22222222) << 1);
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}
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// Next Largest Power of 2
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// Given a binary integer value x, the next largest power of 2 can be computed by a SWAR algorithm
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// that recursively "folds" the upper bits into the lower bits. This process yields a bit vector with
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// the same most significant 1 as x, but all 1's below it. Adding 1 to that value yields the next
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// largest power of 2. For a 32-bit value:
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inline_ udword nlpo2(udword x)
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{
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x |= (x >> 1);
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x |= (x >> 2);
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x |= (x >> 4);
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x |= (x >> 8);
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x |= (x >> 16);
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return x+1;
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}
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//! Test to see if a number is an exact power of two (from Steve Baker's Cute Code Collection)
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inline_ bool IsPowerOfTwo(udword n) { return ((n&(n-1))==0); }
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//! Zero the least significant '1' bit in a word. (from Steve Baker's Cute Code Collection)
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inline_ void ZeroLeastSetBit(udword& n) { n&=(n-1); }
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//! Set the least significant N bits in a word. (from Steve Baker's Cute Code Collection)
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inline_ void SetLeastNBits(udword& x, udword n) { x|=~(~0<<n); }
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//! Classic XOR swap (from Steve Baker's Cute Code Collection)
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//! x ^= y; /* x' = (x^y) */
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//! y ^= x; /* y' = (y^(x^y)) = x */
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//! x ^= y; /* x' = (x^y)^x = y */
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inline_ void Swap(udword& x, udword& y) { x ^= y; y ^= x; x ^= y; }
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//! Little/Big endian (from Steve Baker's Cute Code Collection)
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//!
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//! Extra comments by Kenny Hoff:
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//! Determines the byte-ordering of the current machine (little or big endian)
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//! by setting an integer value to 1 (so least significant bit is now 1); take
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//! the address of the int and cast to a byte pointer (treat integer as an
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//! array of four bytes); check the value of the first byte (must be 0 or 1).
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//! If the value is 1, then the first byte least significant byte and this
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//! implies LITTLE endian. If the value is 0, the first byte is the most
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//! significant byte, BIG endian. Examples:
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//! integer 1 on BIG endian: 00000000 00000000 00000000 00000001
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//! integer 1 on LITTLE endian: 00000001 00000000 00000000 00000000
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//!---------------------------------------------------------------------------
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//! int IsLittleEndian() { int x=1; return ( ((char*)(&x))[0] ); }
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inline_ char LittleEndian() { int i = 1; return *((char*)&i); }
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//!< Alternative abs function
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inline_ udword abs_(sdword x) { sdword y= x >> 31; return (x^y)-y; }
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//!< Alternative min function
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inline_ sdword min_(sdword a, sdword b) { sdword delta = b-a; return a + (delta&(delta>>31)); }
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// Determine if one of the bytes in a 4 byte word is zero
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inline_ BOOL HasNullByte(udword x) { return ((x + 0xfefefeff) & (~x) & 0x80808080); }
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// To find the smallest 1 bit in a word EG: ~~~~~~10---0 => 0----010---0
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inline_ udword LowestOneBit(udword w) { return ((w) & (~(w)+1)); }
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// inline_ udword LowestOneBit_(udword w) { return ((w) & (-(w))); }
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// Most Significant 1 Bit
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// Given a binary integer value x, the most significant 1 bit (highest numbered element of a bit set)
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// can be computed using a SWAR algorithm that recursively "folds" the upper bits into the lower bits.
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// This process yields a bit vector with the same most significant 1 as x, but all 1's below it.
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// Bitwise AND of the original value with the complement of the "folded" value shifted down by one
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// yields the most significant bit. For a 32-bit value:
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inline_ udword msb32(udword x)
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{
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x |= (x >> 1);
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x |= (x >> 2);
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x |= (x >> 4);
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x |= (x >> 8);
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x |= (x >> 16);
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return (x & ~(x >> 1));
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}
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/*
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"Just call it repeatedly with various input values and always with the same variable as "memory".
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The sharpness determines the degree of filtering, where 0 completely filters out the input, and 1
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does no filtering at all.
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I seem to recall from college that this is called an IIR (Infinite Impulse Response) filter. As opposed
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to the more typical FIR (Finite Impulse Response).
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Also, I'd say that you can make more intelligent and interesting filters than this, for example filters
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that remove wrong responses from the mouse because it's being moved too fast. You'd want such a filter
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to be applied before this one, of course."
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(JCAB on Flipcode)
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*/
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inline_ float FeedbackFilter(float val, float& memory, float sharpness)
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{
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ASSERT(sharpness>=0.0f && sharpness<=1.0f && "Invalid sharpness value in feedback filter");
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if(sharpness<0.0f) sharpness = 0.0f;
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else if(sharpness>1.0f) sharpness = 1.0f;
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return memory = val * sharpness + memory * (1.0f - sharpness);
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}
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//! If you can guarantee that your input domain (i.e. value of x) is slightly
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//! limited (abs(x) must be < ((1<<31u)-32767)), then you can use the
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//! following code to clamp the resulting value into [-32768,+32767] range:
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inline_ int ClampToInt16(int x)
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{
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// ASSERT(abs(x) < (int)((1<<31u)-32767));
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int delta = 32767 - x;
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x += (delta>>31) & delta;
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delta = x + 32768;
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x -= (delta>>31) & delta;
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return x;
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}
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// Generic functions
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template<class Type> inline_ void TSwap(Type& a, Type& b) { const Type c = a; a = b; b = c; }
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template<class Type> inline_ Type TClamp(const Type& x, const Type& lo, const Type& hi) { return ((x<lo) ? lo : (x>hi) ? hi : x); }
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template<class Type> inline_ void TSort(Type& a, Type& b)
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{
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if(a>b) TSwap(a, b);
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}
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template<class Type> inline_ void TSort(Type& a, Type& b, Type& c)
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{
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if(a>b) TSwap(a, b);
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if(b>c) TSwap(b, c);
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if(a>b) TSwap(a, b);
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if(b>c) TSwap(b, c);
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}
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// Prevent nasty user-manipulations (strategy borrowed from Charles Bloom)
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// #define PREVENT_COPY(curclass) void operator = (const curclass& object) { ASSERT(!"Bad use of operator ="); }
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// ... actually this is better !
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#define PREVENT_COPY(cur_class) private: cur_class(const cur_class& object); cur_class& operator=(const cur_class& object);
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//! TO BE DOCUMENTED
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#define OFFSET_OF(Class, Member) (size_t)&(((Class*)0)->Member)
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//! TO BE DOCUMENTED
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#define ARRAYSIZE(p) (sizeof(p)/sizeof(p[0]))
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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/**
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* Returns the alignment of the input address.
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* \fn Alignment()
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* \param address [in] address to check
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* \return the best alignment (e.g. 1 for odd addresses, etc)
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*/
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///////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
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FUNCTION ICECORE_API udword Alignment(udword address);
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#define IS_ALIGNED_2(x) ((x&1)==0)
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#define IS_ALIGNED_4(x) ((x&3)==0)
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#define IS_ALIGNED_8(x) ((x&7)==0)
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inline_ void _prefetch(void const* ptr) { (void)*(char const volatile *)ptr; }
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// Compute implicit coords from an index:
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// The idea is to get back 2D coords from a 1D index.
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// For example:
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//
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// 0 1 2 ... nbu-1
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// nbu nbu+1 i ...
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//
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// We have i, we're looking for the equivalent (u=2, v=1) location.
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// i = u + v*nbu
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// <=> i/nbu = u/nbu + v
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// Since 0 <= u < nbu, u/nbu = 0 (integer)
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// Hence: v = i/nbu
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// Then we simply put it back in the original equation to compute u = i - v*nbu
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inline_ void Compute2DCoords(udword& u, udword& v, udword i, udword nbu)
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{
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v = i / nbu;
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u = i - (v * nbu);
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}
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// In 3D: i = u + v*nbu + w*nbu*nbv
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// <=> i/(nbu*nbv) = u/(nbu*nbv) + v/nbv + w
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// u/(nbu*nbv) is null since u/nbu was null already.
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// v/nbv is null as well for the same reason.
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// Hence w = i/(nbu*nbv)
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// Then we're left with a 2D problem: i' = i - w*nbu*nbv = u + v*nbu
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inline_ void Compute3DCoords(udword& u, udword& v, udword& w, udword i, udword nbu, udword nbu_nbv)
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{
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w = i / (nbu_nbv);
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Compute2DCoords(u, v, i - (w * nbu_nbv), nbu);
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}
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#endif // __ICEUTILS_H__
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