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minor comment corrections

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git-svn-id: https://svn.code.sf.net/p/freedos/svn/kernel/trunk@980 6ac86273-5f31-0410-b378-82cca8765d1b
This commit is contained in:
Kenneth J Davis 2004-06-19 19:41:47 +00:00
parent b4ec361ab6
commit 1d684a4eac
1 changed files with 6 additions and 7 deletions
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13
drivers/floppy.asm
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@ -41,7 +41,7 @@ segment HMA_TEXT
global FL_RESET global FL_RESET
FL_RESET: FL_RESET:
pop ax ; return address pop ax ; return address
pop dx ; drive, (DL only, bit 7 set resets both floppy & hd) pop dx ; drive (DL only)
push ax ; restore address push ax ; restore address
mov ah,0 ; BIOS reset diskette & fixed disk mov ah,0 ; BIOS reset diskette & fixed disk
int 13h int 13h
@ -74,7 +74,7 @@ FL_DISKCHANGED:
cmp ah,6 ; if AH==6 then disk change, else error cmp ah,6 ; if AH==6 then disk change, else error
jne fl_dc ; if error, return -1 jne fl_dc ; if error, return -1
mov al, 1 ; set change occurred mov al, 1 ; set change occurred
fl_dc: cbw ; extend AL into AX, AX={1,-1} fl_dc: cbw ; extend AL into AX, AX={1,0,-1}
ret ; note: AH=0 on no change, AL set above ret ; note: AH=0 on no change, AL set above
; ;
@ -112,18 +112,18 @@ fl_common:
push bp ; setup stack frame push bp ; setup stack frame
mov bp,sp mov bp,sp
mov cx,[bp+0Ch] ; cylinder number (lo only if hard) mov cx,[bp+0Ch] ; cylinder number
mov al,1 ; this should be an error code mov al,1 ; this should be an error code
cmp ch,3 ; this code can't write above 3FFh=1023 cmp ch,3 ; this code can't write above 3FFh=1023
ja fl_error ja fl_error ; as cylinder # is limited to 10 bits.
xchg ch,cl ; ch=low 8 bits of cyl number xchg ch,cl ; ch=low 8 bits of cyl number
ror cl,1 ; bits 8-9 of cylinder number... ror cl,1 ; bits 8-9 of cylinder number...
ror cl,1 ; ...to bits 6-7 in CL ror cl,1 ; ...to bits 6-7 in CL
or cl,[bp+0Ah] ; or in the sector number (bits 0-5) or cl,[bp+0Ah] ; or in the sector number (bits 0-5)
mov al,[bp+08h] ; count to read/write (# of sectors) mov al,[bp+08h] ; count of sectors to read/write/...
les bx,[bp+04h] ; Load 32 bit buffer ptr into ES:BX les bx,[bp+04h] ; Load 32 bit buffer ptr into ES:BX
mov dl,[bp+10h] ; drive (if or'ed 80h its a hard drive) mov dl,[bp+10h] ; drive (if or'ed 80h its a hard drive)
@ -133,9 +133,8 @@ fl_common:
sbb al,al ; carry: al=ff, else al=0 sbb al,al ; carry: al=ff, else al=0
and al,ah ; carry: error code, else 0 and al,ah ; carry: error code, else 0
; (Zero transfer count)
fl_error: fl_error:
mov ah,0 ; force into < 255 count mov ah,0 ; extend AL into AX without sign extension
pop bp pop bp
ret 14 ret 14