光盘上的Ghost程序不能用了，还得装个MAXDOS……

时间长了不写东西果然对代码很生疏。

顺便学习一下一个欧拉定理：

a^ψ(p) ≡ 1 (mod p)

CODE:EulerFunc.cpp

#include <stdio.h>

__declspec(naked)int _stdcall GetFactor(int a, int b)
{
        _asm
        {
                PUSH ECX;
                PUSH EDX;
                MOV EAX, [ESP + 0xc];
                MOV ECX, [ESP + 0x10];
lNext:
                CMP EAX, ECX;
                JG lCalc;
                XCHG EAX, ECX;
lCalc:
                CDQ
                IDIV ECX;
                MOV EAX, EDX;
                CMP EDX, 0;
                JE lEnd;
                JMP lNext;
lEnd:
                MOV EAX, ECX;
                POP EDX;
                POP ECX;
                RET 08H;
        }
}

__declspec(naked)int _stdcall EulerFunc(int nData)
{
        _asm
        {
                PUSH EBX;
                PUSH ECX;
                XOR ECX, ECX;
                XOR EBX, EBX;
lNext:
                INC ECX;
                CMP ECX, [ESP + 0xc];
                JG lEnd;
                PUSH [ESP + 0xc];
                PUSH ECX;
                CALL GetFactor;
                CMP EAX, 1;
                JNE lSkip;
                INC EBX;
lSkip:
                JMP lNext;
lEnd:
                MOV EAX, EBX;
                POP ECX;
                POP EBX;
                RET 0x4;
        }
}

void main()
{
        for(int i = 1; i < 100; i++)
        {
                printf("φ(%d) = %d\n", i, EulerFunc(i));
        }
        getchar();
}