#if 0
You will provide your solution to the Data Lab by
editing the collection of functions in this source file.
INTEGER CODING RULES:
Replace the "return" statement in each function with one
or more lines of C code that implements the function. Your code
must conform to the following style:
int Funct(arg1, arg2, ...) {
int var1 = Expr1;
...
int varM = ExprM;
varJ = ExprJ;
...
varN = ExprN;
return ExprR;
}
Each "Expr" is an expression using ONLY the following:
1. Integer constants 0 through 255 (0xFF), inclusive. You are
not allowed to use big constants such as 0xffffffff.
2. Function arguments and local variables (no global variables).
3. Unary integer operations ! ~
4. Binary integer operations & ^ | + << >>
Some of the problems restrict the set of allowed operators even further.
Each "Expr" may consist of multiple operators. You are not restricted to
one operator per line.
You are expressly forbidden to:
1. Use any control constructs such as if, do, while, for, switch, etc.
2. Define or use any macros.
3. Define any additional functions in this file.
4. Call any functions.
5. Use any other operations, such as &&, ||, -, or ?:
6. Use any form of casting.
7. Use any data type other than int. This implies that you
cannot use arrays, structs, or unions.
You may assume that your machine:
1. Uses 2s complement, 32-bit representations of integers.
2. Performs right shifts arithmetically.
3. Has unpredictable behavior when shifting if the shift amount
is less than 0 or greater than 31.
EXAMPLES OF ACCEPTABLE CODING STYLE:
int pow2plus1(int x) {
return (1 << x) + 1;
}
int pow2plus4(int x) {
int result = (1 << x);
result += 4;
return result;
}
FLOATING POINT CODING RULES
For the problems that require you to implement floating-point operations,
the coding rules are less strict. You are allowed to use looping and
conditional control. You are allowed to use both ints and unsigneds.
You can use arbitrary integer and unsigned constants. You can use any arithmetic,
logical, or comparison operations on int or unsigned data.
You are expressly forbidden to:
1. Define or use any macros.
2. Define any additional functions in this file.
3. Call any functions.
4. Use any form of casting.
5. Use any data type other than int or unsigned. This means that you
cannot use arrays, structs, or unions.
6. Use any floating point data types, operations, or constants.
NOTES:
1. Use the dlc (data lab checker) compiler (described in the handout) to
check the legality of your solutions.
2. Each function has a maximum number of operations (integer, logical,
or comparison) that you are allowed to use for your implementation
of the function. The max operator count is checked by dlc.
Note that assignment ('=') is not counted; you may use as many of
these as you want without penalty.
3. Use the btest test harness to check your functions for correctness.
4. Use the BDD checker to formally verify your functions
5. The maximum number of ops for each function is given in the
header comment for each function. If there are any inconsistencies
between the maximum ops in the writeup and in this file, consider
this file the authoritative source.
#endif
int bitXor(int x, int y) {
return ~(~x & ~y) & ~(x & y);
}
int tmin(void) {
return 1<<31;
}
int isTmax(int x) {
return !((~(x+1)^x))&!!(x+1);
}
int allOddBits(int x) {
int a=0xAA<<8;
int c=a|0xAA;
int d=c<<16|c;
return !((x&d)^(d));;
}
int negate(int x) {
return ~x + 1;
}
int isAsciiDigit(int x) {
int a=!(x >> 4 ^0x3);
int b=x&0xF;
int c=~0xA+1;
int e=0x80<<4;
int d=!!((b+c)&(e));
return a&d ;
}
int conditional(int x, int y, int z) {
int a=!!(x^0x0);
int b=~a+1;
int c=~(y&~b)+1;
int d=~(z&b)+1;
return y+z+c+d;
}
int isLessOrEqual(int x, int y) {
int a=x>>31&0x1;
int b=y>>31&0x1;
int c1=(a&~b);
int c2=(~a&b);
int e=y+(~x+1);
int flag=e>>31;
return c1 |(!c2&!flag);
}
int logicalNeg(int x) {
return ((x | (~x +1)) >> 31) + 1;
}
int howManyBits(int x) {
int b16,b8,b4,b2,b1,b0;
int flag=x>>31;
x=(flag&~x)|(~flag&x);
b16=!!(x>>16) <<4;
x>>=b16;
b8=!!(x>>8)<<3;
x >>= b8;
b4 = !!(x >> 4) << 2;
x >>= b4;
b2 = !!(x >> 2) << 1;
x >>= b2;
b1 = !!(x >> 1);
x >>= b1;
b0 = x;
return b0+b1+b2+b4+b8+b16+1;
}
unsigned floatScale2(unsigned uf) {
unsigned exp = (uf&0x7f800000)>>23;
unsigned sign=uf>>31&0x1;
unsigned frac=uf&0x7FFFFF;
unsigned res;
if(exp==0xFF)return uf;
else if(exp==0){
frac <<= 1;
res = (sign << 31) | (exp << 23) | frac;
}
else{
exp++;
res = (sign << 31) | (exp << 23) | frac;
}
return res;
}
int floatFloat2Int(unsigned uf) {
unsigned exp = (uf&0x7f800000)>>23;
int sign=uf>>31&0x1;
unsigned frac=uf&0x7FFFFF;
int E=exp-127;
if(E<0)return 0;
else if(E >= 31){
return 0x80000000u;
}
else{
frac=frac|1<<23;
if(E<23) {
frac>>=(23-E);
}
else{
frac <<= (E - 23);
}
}
if (sign)
return -frac;
else
return frac;
}
unsigned floatPower2(int x) {
if(x>127){
return 0xFF<<23;
}
else if(x<-148)return 0;
else if(x>=-126){
int exp = x + 127;
return (exp << 23);
}
else{
int t = 148 + x;
return (1 << t);
}
}
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