Confusion on pointer

[black_snail]

define FP_SEG(fp) (*((unsigned *)&(fp)+1))
define FP_OFF(fp) (*((unsigned *)&(fp)))

char far * tab;
unsigned int ttseg;
long ttlen;

main()
{
.............
F_1(arg1,&ttseg,&ttlen); /* ttseg = Segment Address
ttlen = Segment length */
FP_SEG(tab) = ttseg;
FP_OFF(tab) = 0;
................

}

Assume the application is like that , What's the functionality of
FP_SEG(tab) = ttseg;
FP_OFF(tab) = 0;

It's running understand MC6.00 + DOS

[jfguo]

define FP_SEG(fp) (*((unsigned *)&(fp)+1))
define FP_OFF(fp) (*((unsigned *)&(fp)))

不是有定义吗

[black_snail]

Means ?

[Iamme]

far 指针的段地址和段长度？

[zxm954712]

define FP_SEG(fp) (*((unsigned *)&(fp)+1)) 表示：
先对指针fp取地址，然后把fp的地址转换成unsigned型，加1，然后取它的值.
define FP_OFF(fp) (*((unsigned *)&(fp)))
对指针fp取地址，然后强制转换成unsigned型，取值