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Revision a70ce33ffb90eff0453b1889537d725130e62236, 1.4 KB
(checked in by H. Peter Anvin <hpa@…>, 3 years ago)
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pxelinux: be more paranoid about saving/restoring flags
Save and restore flags around writechr and the PXE stack call, just in
case the underlying stack does something weird.
Signed-off-by: H. Peter Anvin <hpa@…>
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| 1 | ; |
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| 2 | ; writechr: Write a single character in AL to the console without |
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| 3 | ; mangling any registers. This does raw console writes, |
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| 4 | ; since some PXE BIOSes seem to interfere regular console I/O. |
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| 5 | ; |
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| 6 | %if IS_ISOLINUX |
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| 7 | writechr_full: |
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| 8 | %else |
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| 9 | writechr: |
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| 10 | %endif |
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| 11 | pushfd |
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| 12 | push ds |
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| 13 | push cs |
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| 14 | pop ds |
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| 15 | test byte [UsingVGA], 08h |
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| 16 | jz .videook |
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| 17 | call vgaclearmode |
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| 18 | .videook: |
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| 19 | call write_serial ; write to serial port if needed |
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| 20 | test byte [DisplayCon],01h ; Write to screen? |
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| 21 | jz .nothing |
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| 22 | |
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| 23 | pushad |
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| 24 | mov bh,[BIOS_page] |
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| 25 | push ax |
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| 26 | mov ah,03h ; Read cursor position |
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| 27 | int 10h |
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| 28 | pop ax |
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| 29 | cmp al,8 |
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| 30 | je .bs |
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| 31 | cmp al,13 |
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| 32 | je .cr |
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| 33 | cmp al,10 |
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| 34 | je .lf |
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| 35 | push dx |
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| 36 | mov bh,[BIOS_page] |
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| 37 | mov bl,07h ; White on black |
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| 38 | mov cx,1 ; One only |
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| 39 | mov ah,09h ; Write char and attribute |
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| 40 | int 10h |
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| 41 | pop dx |
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| 42 | inc dl |
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| 43 | cmp dl,[VidCols] |
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| 44 | jna .curxyok |
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| 45 | xor dl,dl |
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| 46 | .lf: inc dh |
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| 47 | cmp dh,[VidRows] |
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| 48 | ja .scroll |
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| 49 | .curxyok: mov bh,[BIOS_page] |
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| 50 | mov ah,02h ; Set cursor position |
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| 51 | int 10h |
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| 52 | .ret: popad |
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| 53 | .nothing: |
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| 54 | pop ds |
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| 55 | popfd |
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| 56 | ret |
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| 57 | .scroll: dec dh |
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| 58 | mov bh,[BIOS_page] |
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| 59 | mov ah,02h |
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| 60 | int 10h |
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| 61 | mov ax,0601h ; Scroll up one line |
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| 62 | mov bh,[ScrollAttribute] |
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| 63 | xor cx,cx |
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| 64 | mov dx,[ScreenSize] ; The whole screen |
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| 65 | int 10h |
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| 66 | jmp short .ret |
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| 67 | .cr: xor dl,dl |
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| 68 | jmp short .curxyok |
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| 69 | .bs: sub dl,1 |
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| 70 | jnc .curxyok |
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| 71 | mov dl,[VidCols] |
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| 72 | sub dh,1 |
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| 73 | jnc .curxyok |
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| 74 | xor dh,dh |
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| 75 | jmp short .curxyok |
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