模拟CPU算术运算的C语言代码

#include <stdio.h> #include <string.h> #define INFGR 0x7F800000 #define INFSM 0x00000000 typedef long MyFloat; union FandL{ float f; unsigned long l; }; /*Transform a string with binary integer to a decimal integer*/ int atoi(char *s) { int res = 0, i; for(i=0; i<32; i++) { res = res << 1; res = res | s[i]; } return res; } /*Transform a decimal number to a string with binary integer*/ char *itoa(int num, char *s) { unsigned int temp = 0x80000000; int i; for(i=0; i<32; i++) { if(num & temp) s[i] = 1; else s[i] = 0; temp = temp >> 1; } return s; } int iadd(int addend, int summand) { char a[32], b[32], res[32]; int i, result; char c = 0; unsigned int temp = 0x80000000; itoa(addend, a); itoa(summand, b); for(i=31; i>=0; i--) { res[i] = a[i] ^ b[i] ^ c; if(a[i]&b[i] || a[i]&c || b[i]&c) c = 1; else c = 0; } result = atoi(res); if((result & temp) && !(addend & temp) && !(summand & temp) || !(result & temp) && (addend & temp) && (summand & temp)) printf("Data overflow!!\n"); return result; } int isub(int minuend, int subtrahend) { int temp; temp = iadd(~subtrahend, 1); return iadd(minuend, temp); } /*Compare two integers, return 1 when a>b, return 0 when a==b, return -1 when a<b*/ int compare(int a, int b) { int c; c = isub(a, b); if(c & 0x80000000) return -1; else if(c == 0) return 0; else return 1; } __int64 imul(int m, int n) { int mult = n; __int64 res = 0, temp; int k = m, nk, dk, ndk, i; mult <<= 1; nk = iadd(~k, 1); dk = k << 1; ndk = nk << 1; for(i=0; i<16; i++) { temp = res & 0xFFFFFFFF00000000; res = res & 0x00000000FFFFFFFF; temp >>= 32; switch(mult & 0x00000007) { case 0: case 7: break; case 1: case 2: temp = iadd((int)temp, k); break; case 5: case 6: temp = iadd((int)temp, nk); break; case 3: temp = iadd((int)temp, dk); break; case 4: temp = iadd((int)temp, ndk); break; } res = res | (temp << 32); res >>= 2; mult >>= 2; } return res; } int idiv(int dividend, int divisor) { __int64 temp, remainder = 0; int quotient = 0; int ndivisor; int i = 0; char sign = 0; if(!dividend) return 0; if((dividend & 0x80000000) ^ (divisor & 0x80000000)) sign = 1; if(dividend & 0x80000000) dividend = iadd(~dividend, 1); if(divisor & 0x80000000) divisor = iadd(~divisor, 1); ndivisor = iadd(~divisor, 1); remainder |= dividend; remainder <<= 1; temp = remainder & 0xFFFFFFFF00000000; remainder &= 0x00000000FFFFFFFF; temp >>= 32; temp = iadd((int)temp, ndivisor); while(i++ < 32) { quotient <<= 1; if((temp & 0x0000000080000000) == 0) quotient |= 0x00000001; remainder |= (temp << 32); remainder <<= 1; temp = remainder & 0xFFFFFFFF00000000; remainder &= 0x00000000FFFFFFFF; temp >>= 32; if((temp & 0x0000000080000000) == 0) temp = iadd((int)temp, ndivisor); else temp = iadd((int)temp, divisor); } if(sign) quotient = iadd(~quotient, 1); return quotient; } int imod(int dividend, int divisor) { __int64 temp, remainder = 0; int ndivisor; int i = 0; if(dividend & 0x80000000) dividend = iadd(~dividend, 1); if(divisor & 0x80000000) divisor = iadd(~divisor, 1); ndivisor = iadd(~divisor, 1); remainder |= dividend; remainder <<= 1; temp = remainder & 0xFFFFFFFF00000000; remainder &= 0x00000000FFFFFFFF; temp >>= 32; temp = iadd((int)temp, ndivisor); while(i++ < 31) { remainder |= (temp << 32); remainder <<= 1; temp = remainder & 0xFFFFFFFF00000000; remainder &= 0x00000000FFFFFFFF; temp >>= 32; if((temp & 0x0000000080000000) == 0) temp = iadd((int)temp, ndivisor); else temp = iadd((int)temp, divisor); } if(temp & 0x0000000080000000) temp = iadd((int)temp, divisor); remainder |= temp << 32; remainder >>= 32; return (int)remainder; } void Int_To_Bina(char* Binary, char* Integer) { int remainder, temp, i, II = 0, k, len = strlen(Integer); while(1){ remainder = 0; i = 0; while(Integer[i] != '\0'){ temp = iadd((int)imul(remainder, 10), isub(Integer[i], '0')); Integer[i++] = iadd(idiv(temp, 2), '0'); remainder = imod(temp, 2); } Binary[II++] = iadd(remainder, '0'); for(k=0; k<len; k++) if(Integer[k] != '0') break; if(k == len) break; } Binary[II] = '\0'; i = isub(strlen(Binary), 1); for(II=0; II<=(i>>1); II++){ temp = Binary[II]; Binary[II] = Binary[isub(i,II)]; Binary[isub(i,II)] = temp; } } void Float_To_Bina(char* FBinary, char* Float) { int i, k=0, carry, temp; int len = strlen(Float); while(k<150){ carry = 0; for(i=len-1; i>=0; i--){ temp = iadd((int)imul(isub(Float[i], '0'), 2), carry); Float[i] = imod(temp, 10) + '0'; carry = idiv(temp, 10); } FBinary[k++] = iadd(carry, '0'); } FBinary[k] = '\0'; } MyFloat atof(char *s) { char Integer[39], Float[39], Binary[279], FBinary[151]; char sign = 0, Find_Dot = 0; int i=0, II=0, FF=0, lenI, power=0, len; MyFloat result = 0; if(s[i] == '-'){ sign = 1; i++; } while(s[i] != '\0'){ if(s[i] == '.'){ Find_Dot = 1; i++; continue; } if(!Find_Dot) Integer[II++] = s[i++]; else Float[FF++] = s[i++]; } Integer[II] = '\0'; Float[FF] = '\0'; if(!II) strcpy(Integer, "0"); if(!FF) strcpy(Float, "0"); Int_To_Bina(Binary, Integer); Float_To_Bina(FBinary, Float); lenI = strlen(Binary); strcat(Binary, FBinary); len = strlen(Binary); for(i=0; i<len; i++) if(Binary[i] == '1') break; if(i==len) return 0; power = isub(isub(lenI, i), 1); for(II=0; II<23; II++){ result <<= 1; if(Binary[++i] == '1') result |= 1; } if(Binary[++i] == '1') /*????*/ result = iadd(result, 1); if(sign) result |= 0x80000000; result |= iadd(power, 127) << 23; return result; } char *Power_Gre_Zero(char *res, long power){ int i, k, carry, temp; for(i=0; i<power; i++){ carry = 0; for(k=39; k>0; k--){ temp = iadd((int)imul(isub(res[k], '0'), 2), carry); res[k] = iadd(imod(temp, 10), '0'); carry = idiv(temp, 10); } } res[40] = '\0'; strcat(res, ".000000"); return res; } char *Power_Les_Zero(char *res, long power){ int k, i, temp, remainder, carry; power = iadd(~power, 1); res[40] = '\0'; strcat(res, ".0000000"); for(k=0; k<power; k++){ remainder = 0; for(i=1; i<48; i++){ if(res[i] == '.') continue; temp = iadd((int)imul(remainder, 10), isub(res[i], '0')); res[i] = iadd(idiv(temp, 2), '0'); remainder = imod(temp, 2); } } if(res[47] - '0' >= 5){ carry = 1; for(i=46; i>25; i--){ res[i] = iadd(res[i], carry); carry = 0; if(res[i] - '0' > 9){ res[i] = '0'; carry = 1; } } } res[47] = '\0'; return res; } char *ftoa(MyFloat f, char *s) { char res[49]; unsigned long tail=0; long temp=0; int i, k=0; long power=(f&0x7F800000)>>23; if(power==255){ strcpy(s,"1.#INF00"); return s; } if(power<=105){ strcpy(s,"0.000000"); return s; } for(i=0; i<48; i++) res[i] = '0'; tail = f & 0x007FFFFF; tail |= 0x00800000; for(i=0; i<24; i++){ temp = (int)imul(temp, 2); if(tail & 0x00800000) temp = iadd(temp, 1); tail <<= 1; } for(i=39; i>31; i--){ res[i] = iadd(imod(temp, 10), '0'); temp = idiv(temp, 10); } res[48] = '\0'; power -= 150; if(power < 0) strcpy(s, Power_Les_Zero(res, power)); else strcpy(s, Power_Gre_Zero(res, power)); if(f & 0x80000000){ s[0] = '-'; k = 1; } for(i=1; i<39; i++) if(s[i] != '0') break; while(i<49) s[k++] = s[i++]; s[47] = '\0'; return s; } MyFloat fadd(MyFloat addend, MyFloat summand) { MyFloat _Addend, _Summand, Greater, Small