| 1 | ; File name : DisplayFormat.asm
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| 2 | ; Project name : Assembly Library
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| 3 | ; Created date : 29.6.2010
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| 4 | ; Last update : 10.8.2010
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| 5 | ; Author : Tomi Tilli
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| 6 | ; Description : Functions for displaying formatted strings.
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| 7 |
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| 8 | ; Section containing code
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| 9 | SECTION .text
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| 10 |
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| 11 | ;--------------------------------------------------------------------
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| 12 | ; DisplayFormat_ParseCharacters
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| 13 | ; Parameters:
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| 14 | ; DS: BDA segment (zero)
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| 15 | ; SS:BP: Pointer to first format parameter (-=2 for next parameter)
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| 16 | ; CS:SI: Pointer to string to format
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| 17 | ; ES:DI: Ptr to cursor location in video RAM
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| 18 | ; Returns:
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| 19 | ; DI: Updated offset to video RAM
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| 20 | ; Corrupts registers:
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| 21 | ; AX, BX, CX, DX, SI, BP
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| 22 | ;--------------------------------------------------------------------
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| 23 | ALIGN JUMP_ALIGN
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| 24 | DisplayFormat_ParseCharacters:
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| 25 | call .ReadCharacterAndTestForNull
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| 26 | jz SHORT .Return
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| 27 | xor cx, cx ; Zero CX for parsing number parameter
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| 28 | cmp al, '%'
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| 29 | je SHORT .FormatParameterEncountered
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| 30 | call DisplayPrint_CharacterFromAL ; Control or printable character
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| 31 | jmp SHORT DisplayFormat_ParseCharacters
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| 32 | ALIGN JUMP_ALIGN
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| 33 | .Return:
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| 34 | ret
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| 35 |
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| 36 | ;--------------------------------------------------------------------
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| 37 | ; .ReadCharacterAndTestForNull
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| 38 | ; Parameters:
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| 39 | ; CS:SI: Pointer next character from string
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| 40 | ; Returns:
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| 41 | ; AL: Character from string
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| 42 | ; SI: Incremented to next character
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| 43 | ; ZF: Set if NULL, cleared if valid character
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| 44 | ; Corrupts registers:
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| 45 | ; Nothing
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| 46 | ;--------------------------------------------------------------------
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| 47 | ALIGN JUMP_ALIGN
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| 48 | .ReadCharacterAndTestForNull:
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| 49 | eSEG cs
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| 50 | lodsb ; Load from CS:SI to AL
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| 51 | test al, al ; NULL to end string?
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| 52 | ret
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| 53 |
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| 54 |
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| 55 | ;--------------------------------------------------------------------
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| 56 | ; .FormatParameterEncountered
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| 57 | ; Parameters:
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| 58 | ; CX: Zero or previous number parameter
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| 59 | ; DS: BDA segment (zero)
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| 60 | ; SS:BP: Pointer to next format parameter
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| 61 | ; CS:SI: Pointer to next format string character
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| 62 | ; ES:DI: Ptr to cursor location in video RAM
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| 63 | ; Returns:
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| 64 | ; SI: Incremented to next character
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| 65 | ; BP: Offset to next format parameter
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| 66 | ; Eventually jumps to DisplayFormat_ParseCharacters
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| 67 | ; Corrupts registers:
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| 68 | ; AX, BX, CX, DX
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| 69 | ;--------------------------------------------------------------------
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| 70 | ALIGN JUMP_ALIGN
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| 71 | .FormatParameterEncountered:
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| 72 | call .ReadCharacterAndTestForNull
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| 73 | jz SHORT .Return
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| 74 | call Char_IsDecimalDigitInAL
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| 75 | jnc SHORT .FormatWithCorrectFormatFunction
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| 76 | ; Fall to .ParseNumberParameterToCX
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| 77 |
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| 78 | ;--------------------------------------------------------------------
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| 79 | ; .ParseNumberParameterToCX
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| 80 | ; Parameters:
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| 81 | ; AL: Number digit from format string
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| 82 | ; CX: Zero or previous number parameter
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| 83 | ; Returns:
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| 84 | ; CX: Updated number parameter
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| 85 | ; Jumps to .FormatParameterEncountered
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| 86 | ; Corrupts registers:
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| 87 | ; AX
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| 88 | ;--------------------------------------------------------------------
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| 89 | .ParseNumberParameterToCX:
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| 90 | sub al, '0' ; Digit '0'...'9' to integer 0...9
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| 91 | mov ah, cl ; Previous number parameter to AH
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| 92 | aad ; AL += (AH * 10)
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| 93 | mov cl, al ; Updated number parameter now in CX
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| 94 | jmp SHORT .FormatParameterEncountered
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| 95 |
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| 96 | ;--------------------------------------------------------------------
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| 97 | ; .FormatWithCorrectFormatFunction
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| 98 | ; Parameters:
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| 99 | ; AL: Format placeholder character (non digit character after '%')
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| 100 | ; CX: Number parameter (zero if no number parameter present)
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| 101 | ; DS: BDA segment (zero)
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| 102 | ; SS:BP: Pointer to format parameter
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| 103 | ; CS:SI: Pointer to next format string character
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| 104 | ; ES:DI: Ptr to cursor location in video RAM
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| 105 | ; Returns:
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| 106 | ; Eventually jumps to DisplayFormat_ParseCharacters
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| 107 | ; Corrupts registers:
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| 108 | ; AX, BX, CX, DX
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| 109 | ;--------------------------------------------------------------------
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| 110 | ALIGN JUMP_ALIGN
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| 111 | .FormatWithCorrectFormatFunction:
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| 112 | xor bx, bx ; Zero lookup index
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| 113 | ALIGN JUMP_ALIGN
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| 114 | .PlaceholderComparisonLoop:
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| 115 | cmp al, [cs:bx+.rgcFormatCharToLookupIndex]
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| 116 | je SHORT .JumpToFormatPlaceholder
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| 117 | inc bx
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| 118 | cmp bl, .EndOFrgcFormatCharToLookupIndex - .rgcFormatCharToLookupIndex
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| 119 | jb SHORT .PlaceholderComparisonLoop ; Loop
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| 120 | call DisplayPrint_CharacterFromAL ; Display unsupported format character
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| 121 | ; Fall to .UpdateSpacesToAppendAfterPrintingSingleCharacter
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| 122 |
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| 123 | ;--------------------------------------------------------------------
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| 124 | ; .UpdateSpacesToAppendAfterPrintingSingleCharacter
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| 125 | ; .UpdateSpacesToAppend
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| 126 | ; Parameters:
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| 127 | ; BX: Number of characters printed (.UpdateSpacesToAppend only)
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| 128 | ; CX: Number parameter (zero if no number parameter present)
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| 129 | ; DS: BDA segment (zero)
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| 130 | ; SS:BP: Pointer to format parameter
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| 131 | ; CS:SI: Pointer to next format string character
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| 132 | ; ES:DI: Ptr to cursor location in video RAM
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| 133 | ; Returns:
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| 134 | ; CX: Number of spaces to append
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| 135 | ; Jumps to .PrepareToFormatNextParameter
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| 136 | ; Corrupts registers:
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| 137 | ; AX, BX, CX, DX
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| 138 | ;--------------------------------------------------------------------
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| 139 | ALIGN JUMP_ALIGN
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| 140 | .UpdateSpacesToAppendAfterPrintingSingleCharacter:
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| 141 | mov bx, 1
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| 142 | ALIGN JUMP_ALIGN
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| 143 | .UpdateSpacesToAppend:
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| 144 | jcxz .PrepareToFormatNextParameter
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| 145 | sub cx, bx ; Number of spaces to append
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| 146 | jle SHORT .PrepareToFormatNextParameter
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| 147 | mov al, ' '
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| 148 | call DisplayPrint_RepeatCharacterFromALwithCountInCX
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| 149 | ; Fall to .PrepareToFormatNextParameter
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| 150 |
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| 151 | ;--------------------------------------------------------------------
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| 152 | ; .PrepareToFormatNextParameter
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| 153 | ; Parameters:
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| 154 | ; DS: BDA segment (zero)
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| 155 | ; SS:BP: Pointer to format parameter
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| 156 | ; CS:SI: Pointer to next format string character
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| 157 | ; ES:DI: Ptr to cursor location in video RAM
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| 158 | ; Returns:
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| 159 | ; BP: Adjusted to point next stack parameter
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| 160 | ; Jumps to DisplayFormat_ParseCharacters
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| 161 | ; Corrupts registers:
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| 162 | ; Nothing
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| 163 | ;--------------------------------------------------------------------
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| 164 | ALIGN JUMP_ALIGN
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| 165 | .PrepareToFormatNextParameter:
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| 166 | dec bp
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| 167 | dec bp
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| 168 | jmp SHORT DisplayFormat_ParseCharacters
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| 169 |
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| 170 |
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| 171 | ;--------------------------------------------------------------------
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| 172 | ; .JumpToFormatPlaceholder
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| 173 | ; Parameters:
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| 174 | ; BX: Lookup index for format function
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| 175 | ; CX: Number parameter (zero if no number parameter present)
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| 176 | ; DS: BDA segment (zero)
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| 177 | ; SS:BP: Pointer to next format parameter
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| 178 | ; CS:SI: Pointer to next format string character
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| 179 | ; ES:DI: Ptr to cursor location in video RAM
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| 180 | ; Returns:
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| 181 | ; Eventually jumps to DisplayFormat_ParseCharacters
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| 182 | ; Corrupts registers:
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| 183 | ; AX, BX, DX
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| 184 | ;--------------------------------------------------------------------
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| 185 | ALIGN JUMP_ALIGN
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| 186 | .JumpToFormatPlaceholder:
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| 187 | shl bx, 1 ; Shift for WORD lookup
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| 188 | jmp [cs:bx+.rgfnFormatParameter]
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| 189 |
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| 190 | ALIGN JUMP_ALIGN
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| 191 | .a_FormatAttributeForNextCharacter:
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| 192 | mov bl, [bp]
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| 193 | xchg bl, [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.bAttribute]
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| 194 | call .ReadCharacterAndTestForNull
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| 195 | jz SHORT .Return
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| 196 | call DisplayPrint_CharacterFromAL
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| 197 | mov [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.bAttribute], bl
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| 198 | jmp SHORT .UpdateSpacesToAppendAfterPrintingSingleCharacter
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| 199 |
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| 200 | ALIGN JUMP_ALIGN
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| 201 | .A_FormatAttributeForRemainingString:
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| 202 | mov al, [bp]
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| 203 | mov [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.bAttribute], al
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| 204 | jmp SHORT .PrepareToFormatNextParameter
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| 205 |
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| 206 | ALIGN JUMP_ALIGN
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| 207 | .d_FormatSignedDecimalWord:
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| 208 | mov ax, [bp]
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| 209 | call DisplayPrint_SignedDecimalIntegerFromAX
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| 210 | jmp SHORT .UpdateSpacesToAppend
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| 211 |
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| 212 | ALIGN JUMP_ALIGN
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| 213 | .u_FormatUnsignedDecimalWord:
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| 214 | mov ax, [bp]
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| 215 | mov bx, 10
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| 216 | call DisplayPrint_WordFromAXWithBaseInBX
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| 217 | jmp SHORT .UpdateSpacesToAppend
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| 218 |
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| 219 | ALIGN JUMP_ALIGN
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| 220 | .x_FormatHexadecimalWord:
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| 221 | mov ax, [bp]
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| 222 | mov bx, 16
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| 223 | call DisplayPrint_WordFromAXWithBaseInBX
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| 224 | inc bx ; Increment character count for 'h'
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| 225 | mov al, 'h'
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| 226 | call DisplayPrint_CharacterFromAL
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| 227 | jmp SHORT .UpdateSpacesToAppend
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| 228 |
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| 229 | ALIGN JUMP_ALIGN
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| 230 | .s_FormatStringFromSegmentCS:
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| 231 | xchg si, [bp]
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| 232 | call DisplayPrint_NullTerminatedStringFromCSSI
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| 233 | mov si, [bp] ; Restore SI
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| 234 | jmp SHORT .UpdateSpacesToAppend
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| 235 |
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| 236 | ALIGN JUMP_ALIGN
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| 237 | .S_FormatStringFromFarPointer:
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| 238 | xchg si, [bp]
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| 239 | mov bx, [bp-2]
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| 240 | call DisplayPrint_NullTerminatedStringFromBXSI
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| 241 | mov si, [bp] ; Restore SI
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| 242 | jmp SHORT .UpdateSpacesToAppendWithDWordParameter
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| 243 |
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| 244 | ALIGN JUMP_ALIGN
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| 245 | .c_FormatCharacter:
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| 246 | mov al, [bp]
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| 247 | jmp SHORT .FormatSingleCharacterFromAL
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| 248 |
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| 249 | ALIGN JUMP_ALIGN
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| 250 | .t_FormatRepeatCharacter:
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| 251 | mov cx, [bp-2]
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| 252 | mov bx, cx
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| 253 | mov al, [bp]
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| 254 | call DisplayPrint_RepeatCharacterFromALwithCountInCX
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| 255 | jmp SHORT .UpdateSpacesToAppendWithDWordParameter
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| 256 |
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| 257 | ALIGN JUMP_ALIGN
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| 258 | .percent_FormatPercent:
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| 259 | mov al, '%'
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| 260 | inc bp ; Adjust here since...
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| 261 | inc bp ; ...no parameter on stack
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| 262 | ; Fall to .FormatSingleCharacterFromAL
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| 263 |
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| 264 | ALIGN JUMP_ALIGN
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| 265 | .FormatSingleCharacterFromAL:
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| 266 | call DisplayPrint_CharacterFromAL
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| 267 | jmp .UpdateSpacesToAppendAfterPrintingSingleCharacter
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| 268 |
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| 269 | ALIGN JUMP_ALIGN
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| 270 | .UpdateSpacesToAppendWithDWordParameter:
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| 271 | dec bp
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| 272 | dec bp
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| 273 | jmp .UpdateSpacesToAppend
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| 274 |
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| 275 |
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| 276 | ; Table for converting format character to jump table index
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| 277 | .rgcFormatCharToLookupIndex:
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| 278 | db "aAduxsSct%"
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| 279 | .EndOFrgcFormatCharToLookupIndex:
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| 280 |
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| 281 | ; Jump table
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| 282 | ALIGN WORD_ALIGN
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| 283 | .rgfnFormatParameter:
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| 284 | dw .a_FormatAttributeForNextCharacter
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| 285 | dw .A_FormatAttributeForRemainingString
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| 286 | dw .d_FormatSignedDecimalWord
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| 287 | dw .u_FormatUnsignedDecimalWord
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| 288 | dw .x_FormatHexadecimalWord
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| 289 | dw .s_FormatStringFromSegmentCS
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| 290 | dw .S_FormatStringFromFarPointer
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| 291 | dw .c_FormatCharacter
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| 292 | dw .t_FormatRepeatCharacter
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| 293 | dw .percent_FormatPercent
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