华中科技大学——logisim 3.数据表示实验.zip

// file : float_add_overflow.c # include "stdio.h" union { char c[4]; float f; int i; } t1,t2,t3,t4; //输出字符的十六进制编码 void char_hex_out(char a) { const char HEX[]="0123456789ABCDEF"; int index=a&0x0F; printf("%c%c", HEX[(a&0xF0)>>4],HEX[a&0x0F]); } //输出4个字节数据的十六进制编码，可用于输出4字节变量的机器码 void four_byte_out (char *addr) { char_hex_out (*(addr +3)); //输出指针变量的值，指针本质上是内存地址，无符号数 char_hex_out (*(addr +2)); //假设采用小端存储 char_hex_out (*(addr +1)); char_hex_out (*(addr +0)); printf("\n"); } void float_add_overflow() { t1.i=0x7F000000; t2.i=0x7F000000; t3.f=t1.f+t2.f; four_byte_out (&t1.f); //该函数见1.1.3节程序中的定义 four_byte_out (&t2.f); four_byte_out (&t3.f); printf("t1 = %.60f \n",t1.f); printf("t2 = %.60f \n",t2.f); printf("t1+t2 = %.60f \n",t3.f); } void float_sub_overflow() { t1.i=0x00C00000; t2.i=0x00800000; t3.f=t1.f-t2.f; four_byte_out (&t1.f); //该函数见1.1.3节程序中的定义 four_byte_out (&t2.f); four_byte_out (&t3.f); printf("t1 = %.61f \n",t1.f); printf("t2 = %.61f \n",t2.f); printf("t1-t2 = %.61f \n",t3.f); } main() { float_add_overflow(); float_sub_overflow(); }