| [2] | 1 | ; File name : prntbios.asm
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| 2 | ; Project name : Print library
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| 3 | ; Created date : 7.12.2009
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| 4 | ; Last update : 17.1.2010
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| 5 | ; Author : Tomi Tilli
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| 6 | ; Description : ASM library to for character and string
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| 7 | ; printing using BIOS.
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| 8 |
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| 9 | ;--------------- Equates -----------------------------
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| 10 |
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| 11 | ; Int 10h (BIOS) functions
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| 12 | FN_BIOS_WR_CHAR_TEL EQU 0Eh ; Teletype Output
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| 13 |
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| 14 |
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| 15 | ;-------------- Public functions ---------------------
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| 16 | ; Section containing code
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| 17 | SECTION .text
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| 18 |
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| 19 | ;--------------------------------------------------------------------
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| 20 | ; Prints character. All character printing functions must
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| 21 | ; use this macro to print characters (so printing implementation
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| 22 | ; can be easily modified when needed).
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| 23 | ;
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| 24 | ; PRINT_CHAR
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| 25 | ; Parameters:
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| 26 | ; DL: Character to print
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| 27 | ; Returns:
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| 28 | ; Nothing
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| 29 | ; Corrupts registers:
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| 30 | ; AX
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| 31 | ;--------------------------------------------------------------------
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| 32 | %macro PRINT_CHAR 0
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| 33 | call Print_BiosTeleChar
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| 34 | %endmacro
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| 35 |
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| 36 | ALIGN JUMP_ALIGN
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| 37 | Print_BiosTeleChar:
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| 38 | push bp ; Save because of buggy BIOSes
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| 39 | push bx
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| 40 | mov ah, FN_BIOS_WR_CHAR_TEL
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| 41 | mov al, dl ; Copy char to write
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| 42 | xor bx, bx ; Page 0
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| 43 | int 10h
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| 44 | pop bx
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| 45 | pop bp
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| 46 | ret
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| 47 |
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| 48 |
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| 49 | ;--------------------------------------------------------------------
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| 50 | ; Prints string. All string printing functions must
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| 51 | ; use this macro to print strings (so printing implementation
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| 52 | ; can be easily modified when needed).
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| 53 | ;
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| 54 | ; PRINT_STR
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| 55 | ; Parameters:
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| 56 | ; DS:DX: Ptr to STOP terminated string
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| 57 | ; Returns:
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| 58 | ; Nothing
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| 59 | ; Corrupts registers:
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| 60 | ; AX
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| 61 | ;--------------------------------------------------------------------
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| 62 | %macro PRINT_STR 0
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| 63 | push dx
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| 64 | call Print_BiosTeleStr
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| 65 | pop dx
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| 66 | %endmacro
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| 67 |
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| 68 |
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| 69 | ;--------------------------------------------------------------------
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| 70 | ; Prints string and returns number of characters printed.
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| 71 | ; All string printing functions must use this macro to print strings
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| 72 | ; (so printing implementation can be easily modified when needed).
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| 73 | ;
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| 74 | ; PRINT_STR_LEN
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| 75 | ; Parameters:
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| 76 | ; DS:DX: Ptr to STOP terminated string
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| 77 | ; Returns:
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| 78 | ; DX: Number of characters printed
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| 79 | ; Corrupts registers:
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| 80 | ; AX
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| 81 | ;--------------------------------------------------------------------
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| 82 | %macro PRINT_STR_LEN 0
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| 83 | call Print_BiosTeleStr
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| 84 | %endmacro
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| 85 |
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| 86 | ALIGN JUMP_ALIGN
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| 87 | Print_BiosTeleStr:
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| 88 | push bp ; Save because of buggy BIOSes
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| 89 | push si
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| 90 | push bx
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| 91 | mov si, dx ; Copy offset to string
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| 92 | xor dx, dx ; Zero char counter
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| 93 | xor bx, bx ; Page 0
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| 94 | cld ; LODSB to increment SI
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| 95 | ALIGN JUMP_ALIGN
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| 96 | .CharLoop:
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| 97 | lodsb ; Load char from [DS:SI] to AL
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| 98 | cmp al, STOP ; End of string?
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| 99 | je .Return ; If so, return
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| 100 | mov ah, FN_BIOS_WR_CHAR_TEL ; Some BIOSes corrupt AH when returning
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| 101 | int 10h
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| 102 | inc dx ; Increment chars printed
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| 103 | jmp .CharLoop ; Loop while chars left
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| 104 | ALIGN JUMP_ALIGN
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| 105 | .Return:
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| 106 | pop bx
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| 107 | pop si
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| 108 | pop bp
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| 109 | ret
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