请教各位汇编高手关于GDT描述符数据定义问题。
dd gdt_table
;********* GDT TABLE
gdt_table:
null_desc desc 0,0,0
flat_code desc 0, 0xFFFFF, D_CODE + D_READ + D_BIG + D_BIG_LIM
flat_data desc 0, 0xFFFFF, D_DATA + D_WRITE + D_BIG + D_BIG_LIM
注:D_CODE,D_READ,D_BIG,D_BIG_LIM,D_DATA,D_WRITE等有定义如下:
D_CODE EQU 1800h ;Code segment
D_WRITE EQU 200h ;Writable (Data segments only)
D_READ EQU 200h ;Readable (Code segments only)
D_BIG EQU 40h ;Default to 32 bit mode (USE32)
D_BIG_LIM EQU 80h ;Limit is in 4K units
(以上代码NASM下通过)
问:desc什么意思?GDT描述符不是8个字节么,怎么用dd gdt_table?
这三个gdt描述符应该是怎么样的呢,具体。
请各位高手指点,谢过。