pokeb.c

来自「一个类linux的dos下开发的操作系统.」· C语言 代码 · 共 13 行

__inline__ void pokeb(unsigned short sel, unsigned long off, unsigned char val)
{
	__asm__ __volatile__("mov %0,%%es\n"
		"es\n"
		"movb %b1,(%2)"
		:
/* "q" means EAX, EBX, ECX, EDX i.e. one of the byte-addressable registers

xxx - "r" means any reg, but you want one of the regs than can be
used in an address without a prefix: EBP, EBX, ESI, EDI */
		: "m"(sel), "q"(val), "r"(off));
}