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| Printing a string directly to the video memory https://forum.osdev.org/viewtopic.php?f=13&t=31090 |
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| Author: | leosa99 [ Sun Dec 18, 2016 10:31 am ] |
| Post subject: | Printing a string directly to the video memory |
Hi ! I made a function to print the SI register on the screen directly through the video memory. It's weird but this function only write the first character ... Code: writeCharacterToVideoMemoryFunc: ; al=character ah=attributes cx=offset(byte) mov esi, 0xB8000 add si, cx mov byte [esi], al mov byte [esi+1], ah ret writeSIToVideoMemory: ; cx=offset mov al, [si] cmp al, 0 je end mov ah, 00001111b call writeCharacterToVideoMemoryFunc inc si add cx, 2d ; inc cx 2 times jmp writeSIToVideoMemory end: ret I call it with this code : Code: mov si, MSG mov cx, 40d call writeSIToVideoMemory jmp $ MSG: db "OK !", 0 I run it in protected mode. Thanks ! |
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| Author: | iansjack [ Sun Dec 18, 2016 10:34 am ] |
| Post subject: | Re: Printing a string directly to the video memory |
Your WriteCharacter routine trashes SI, which is going to cause problems. |
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| Author: | leosa99 [ Sun Dec 18, 2016 11:09 am ] |
| Post subject: | Re: Printing a string directly to the video memory |
I'm dumb. Thanks |
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