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Using Register Addressing
Instructions and Op Codes
Overview of my Compiler
16 bit Date Extraction
FAT12 Floppy Disk Access
32 bit to 16 bit File Size
Finding Free Disk Space
16bit Memory Routines
Mouse Callback
Floppy Disk Parameters
Registers
The Root Directory
Using the Stack
Creating a Boot Disk
Direct To Screen Output
16 bit Time Extraction
Basic Display Code

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Information on FAT16

Time Code

Extracting the Time

The file time is held in a 16 bit value in the following format.

An example showing one way of extracting the Time from the 16 bit value.

; Extracts the File time from a 16 bit value ; 00-04 - Seconds to the nearest 2 seconds 5bits ; 05-0A - Minutes (0-59) 6bits ; 0B-0F - Hours (0-23) 5bits ; Pass AX = Time as File Time ; Returns BX=Minutes, AH=Hours, AL=Seconds SubConvertWordToTime: PUSH ECX MOV BX, AX SHL BX, 0x03 SHL BH, 0x02 SHR BH, 0x02 MOV BL, BH MOV BH, 0x00 ; BX = Minutes SHL AL, 0x03 SHR AL, 0x03 ; AL = Seconds SHR AH, 0x03 ; AH = Hours POP ECX RET

Creating a Date

There will be times when you need to save the time back to the disk.

; Creates a Time as a 16 bit value ; Pass BX=Minutes, AH=Hours, AL=Seconds ; Returns AX=Time as 16 bits SubConvertTimeToWord: PUSH ECX MOV BH, 0x00 SHL BX, 0x05 SHL AH, 0x03 ADD AX, BX POP ECX RET