求救！急！！如何在C语言中使用INT 13 EXTENSION？

[acqy]

现在我已经知道用INT 13 EXTENSION读取磁盘扇区要调用42h号子功能，有文档显示如下：
INT 13 - IBM/MS INT 13 Extensions - EXTENDED READ
AH = 42h
DL = drive number
DS:SI -> disk address packet (see #00272)
Return: CF clear if successful
AH = 00h
CF set on error
AH = error code (see #00234)
disk address packet's block count field set to number of blocks
successfully transferred
SeeAlso: AH=02h,AH=41h"INT 13 Ext",AH=43h"INT 13 Ext"

Format of disk address packet:
Offset Size Description (Table 00272)
00h BYTE 10h (size of packet)
01h BYTE reserved (0)
02h WORD number of blocks to transfer (max 007Fh for Phoenix EDD)
04h DWORD -> transfer buffer
08h QWORD starting absolute block number
(for non-LBA devices, compute as
(Cylinder*NumHeads + SelectedHead) * SectorPerTrack +
SelectedSector - 1
请问有谁知道packet是什么吗？能否通过C语言程序来举例说明这个功能的用法。谢谢！