| 1 | ; File name : DisplayCharOut.asm
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| 2 | ; Project name : Assembly Library
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| 3 | ; Created date : 26.6.2010
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| 4 | ; Last update : 18.9.2010
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| 5 | ; Author : Tomi Tilli
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| 6 | ; Description : Functions for outputting characters to video memory.
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| 7 | ; These functions are meant to be called by Display_CharacterFromAL
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| 8 | ; and Display_RepeatCharacterFromAL using function pointer
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| 9 | ; stored in DISPLAY_CONTEXT.
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| 10 |
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| 11 | ; Section containing code
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| 12 | SECTION .text
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| 13 |
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| 14 | ;--------------------------------------------------------------------
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| 15 | ; WAIT_RETRACE_IF_NECESSARY_THEN
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| 16 | ; Parameters:
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| 17 | ; AL: Character to output
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| 18 | ; AH: Attribute to output (stosw only)
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| 19 | ; DS: BDA segment (zero)
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| 20 | ; ES:DI: Ptr to video memory where to output
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| 21 | ; Returns:
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| 22 | ; DI: Incremented for next character
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| 23 | ; Corrupts registers:
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| 24 | ; AX, DX
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| 25 | ;--------------------------------------------------------------------
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| 26 | %macro WAIT_RETRACE_IF_NECESSARY_THEN 1
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| 27 | %ifdef ELIMINATE_CGA_SNOW
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| 28 | %ifidn %1, stosb
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| 29 | call StosbWithoutCgaSnow
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| 30 | %else
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| 31 | call StoswWithoutCgaSnow
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| 32 | %endif
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| 33 | %else
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| 34 | %1 ; STOSB or STOSW
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| 35 | %endif
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| 36 | %endmacro
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| 37 |
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| 38 |
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| 39 | ;--------------------------------------------------------------------
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| 40 | ; DisplayCharOut_TeletypeOutputWithAttribute
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| 41 | ; DisplayCharOut_TeletypeOutput
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| 42 | ; Parameters:
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| 43 | ; AL: Character to output
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| 44 | ; AH: Attribute to output
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| 45 | ; DS: BDA segment (zero)
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| 46 | ; ES:DI: Ptr to video memory where to output
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| 47 | ; Returns:
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| 48 | ; DI: Incremented for next character
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| 49 | ; Corrupts registers:
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| 50 | ; AX, DX
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| 51 | ;--------------------------------------------------------------------
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| 52 | ALIGN JUMP_ALIGN
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| 53 | DisplayCharOut_TeletypeOutputWithAttribute:
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| 54 | cmp al, ' ' ; Printable character?
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| 55 | jb SHORT DisplayCharOut_BiosTeletypeOutput
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| 56 | WAIT_RETRACE_IF_NECESSARY_THEN stosw
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| 57 | ret
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| 58 |
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| 59 | ALIGN JUMP_ALIGN
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| 60 | DisplayCharOut_TeletypeOutput:
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| 61 | cmp al, ' ' ; Printable character?
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| 62 | jae SHORT DisplayCharOut_Character
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| 63 | ; Fall to DisplayCharOut_BiosTeletypeOutput
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| 64 |
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| 65 | ;--------------------------------------------------------------------
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| 66 | ; DisplayCharOut_BiosTeletypeOutput
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| 67 | ; Parameters:
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| 68 | ; AL: Control character
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| 69 | ; DS: BDA segment (zero)
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| 70 | ; ES:DI: Ptr to video memory where to output
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| 71 | ; Returns:
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| 72 | ; DI: Incremented for next character
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| 73 | ; Corrupts registers:
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| 74 | ; AX, DX
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| 75 | ;--------------------------------------------------------------------
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| 76 | ALIGN JUMP_ALIGN
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| 77 | DisplayCharOut_BiosTeletypeOutput:
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| 78 | push ax
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| 79 | call DisplayCursor_SynchronizeCoordinatesToHardware
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| 80 | pop ax
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| 81 | call .OutputCharacterWithBIOS
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| 82 | call DisplayCursor_GetHardwareCoordinatesToAX
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| 83 | jmp DisplayCursor_SetCoordinatesFromAX
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| 84 |
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| 85 | ;--------------------------------------------------------------------
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| 86 | ; .OutputCharacterWithBIOS
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| 87 | ; Parameters:
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| 88 | ; AL: Character to output
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| 89 | ; DS: BDA segment
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| 90 | ; Returns:
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| 91 | ; Nothing
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| 92 | ; Corrupts registers:
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| 93 | ; AX
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| 94 | ;--------------------------------------------------------------------
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| 95 | ALIGN JUMP_ALIGN
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| 96 | .OutputCharacterWithBIOS:
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| 97 | push bx
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| 98 | mov ah, TELETYPE_OUTPUT
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| 99 | mov bh, [VIDEO_BDA.bActivePage]
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| 100 | int BIOS_VIDEO_INTERRUPT_10h
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| 101 | pop bx
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| 102 | ret
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| 103 |
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| 104 |
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| 105 | ;--------------------------------------------------------------------
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| 106 | ; DisplayCharOut_Attribute
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| 107 | ; DisplayCharOut_Character
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| 108 | ; DisplayCharOut_CharacterWithAttribute
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| 109 | ; Parameters:
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| 110 | ; AL: Character to output
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| 111 | ; AH: Attribute to output
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| 112 | ; DS: BDA segment (zero)
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| 113 | ; ES:DI: Ptr to video memory where to output
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| 114 | ; Returns:
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| 115 | ; DI: Incremented for next character
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| 116 | ; Corrupts registers:
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| 117 | ; AX, DX
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| 118 | ;--------------------------------------------------------------------
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| 119 | ALIGN JUMP_ALIGN
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| 120 | DisplayCharOut_Attribute:
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| 121 | xchg al, ah ; Swap character and attribute
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| 122 | inc di ; Skip character
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| 123 | WAIT_RETRACE_IF_NECESSARY_THEN stosb
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| 124 | ret
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| 125 |
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| 126 | ALIGN JUMP_ALIGN
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| 127 | DisplayCharOut_Character:
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| 128 | WAIT_RETRACE_IF_NECESSARY_THEN stosb
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| 129 | inc di ; Skip attribute
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| 130 | ret
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| 131 |
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| 132 | ALIGN JUMP_ALIGN
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| 133 | DisplayCharOut_CharacterWithAttribute:
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| 134 | WAIT_RETRACE_IF_NECESSARY_THEN stosw
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| 135 | ret
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| 136 |
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| 137 |
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| 138 | ;--------------------------------------------------------------------
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| 139 | ; DisplayCharOut_WriteCharacterToBuffer
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| 140 | ; Parameters:
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| 141 | ; AL: Character to output
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| 142 | ; DS: BDA segment (zero)
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| 143 | ; ES:DI: Ptr to destination string buffer
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| 144 | ; DISPLAY_CONTEXT.wCharOutParam: Offset to end of buffer (one past last)
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| 145 | ; Returns:
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| 146 | ; ES:DI: Updated for next character
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| 147 | ; Corrupts registers:
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| 148 | ; AX, DX
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| 149 | ;--------------------------------------------------------------------
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| 150 | ALIGN JUMP_ALIGN
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| 151 | DisplayCharOut_WriteCharacterToBuffer:
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| 152 | cmp di, [VIDEO_BDA.displayContext+DISPLAY_CONTEXT.wCharOutParam]
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| 153 | jae SHORT .BufferFull
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| 154 | stosb
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| 155 | .BufferFull:
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| 156 | ret
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| 157 |
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| 158 |
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| 159 | ; STOSB and STOSW replacement functions to prevent CGA snow. These will slow
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| 160 | ; drawing a lot so use them only if it is necessary to eliminate CGA snow.
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| 161 | %ifdef ELIMINATE_CGA_SNOW
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| 162 |
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| 163 | OFFSET_TO_CGA_STATUS_REGISTER EQU 6 ; Base port 3D4h + 6 = 3DAh
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| 164 | CGA_STATUS_REGISTER EQU 3DAh
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| 165 |
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| 166 | ;--------------------------------------------------------------------
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| 167 | ; WAIT_UNTIL_SAFE_CGA_WRITE
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| 168 | ; Parameters:
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| 169 | ; DX: CGA Status Register Address (3DAh)
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| 170 | ; Returns:
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| 171 | ; Interrupts disabled
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| 172 | ; Corrupts registers:
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| 173 | ; AL
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| 174 | ;--------------------------------------------------------------------
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| 175 | %macro WAIT_UNTIL_SAFE_CGA_WRITE 0
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| 176 | cli ; Interrupt request would mess up timing
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| 177 | %%WaitUntilNotInRetrace:
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| 178 | in al, dx
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| 179 | shr al, 1 ; 1 = Bit 0: A 1 indicates that regen-buffer memory access can be
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| 180 | ; made without interfering with the display. (H or V retrace)
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| 181 | jc SHORT %%WaitUntilNotInRetrace
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| 182 | sti
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| 183 | nop ; Should have time to serve IRQ here
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| 184 | cli
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| 185 | %%WaitUntilNextRetraceStarts:
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| 186 | in al, dx
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| 187 | shr al, 1
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| 188 | jnc SHORT %%WaitUntilNextRetraceStarts
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| 189 | %endmacro
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| 190 |
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| 191 | ;--------------------------------------------------------------------
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| 192 | ; StosbWithoutCgaSnow
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| 193 | ; StoswWithoutCgaSnow
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| 194 | ; Parameters:
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| 195 | ; AL: Character to output
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| 196 | ; AH: Attribute to output (StoswWithoutCgaSnow only)
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| 197 | ; DS: BDA segment (zero)
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| 198 | ; ES:DI: Ptr to video memory where to output
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| 199 | ; Returns:
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| 200 | ; DI: Incremented for next character
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| 201 | ; Corrupts registers:
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| 202 | ; AX, DX
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| 203 | ;--------------------------------------------------------------------
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| 204 | ALIGN JUMP_ALIGN
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| 205 | StosbWithoutCgaSnow:
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| 206 | call LoadAndVerifyStatusRegisterFromBDA
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| 207 | jne SHORT .StosbWithoutWaitSinceUnknownPort
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| 208 |
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| 209 | mov ah, al
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| 210 | WAIT_UNTIL_SAFE_CGA_WRITE
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| 211 | mov al, ah
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| 212 | stosb
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| 213 | sti
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| 214 | ret
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| 215 | ALIGN JUMP_ALIGN
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| 216 | .StosbWithoutWaitSinceUnknownPort:
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| 217 | stosb
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| 218 | ret
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| 219 |
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| 220 | ALIGN JUMP_ALIGN
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| 221 | StoswWithoutCgaSnow:
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| 222 | call LoadAndVerifyStatusRegisterFromBDA
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| 223 | jne SHORT .StoswWithoutWaitSinceUnknownPort
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| 224 |
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| 225 | push bx
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| 226 | xchg bx, ax
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| 227 | WAIT_UNTIL_SAFE_CGA_WRITE
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| 228 | xchg ax, bx
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| 229 | stosw
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| 230 | pop bx
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| 231 | sti
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| 232 | ret
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| 233 | ALIGN JUMP_ALIGN
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| 234 | .StoswWithoutWaitSinceUnknownPort:
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| 235 | stosw
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| 236 | ret
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| 237 |
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| 238 | ;--------------------------------------------------------------------
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| 239 | ; LoadAndVerifyStatusRegisterFromBDA
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| 240 | ; Parameters:
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| 241 | ; DS: BDA segment (zero)
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| 242 | ; Returns:
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| 243 | ; DX: CGA Status Register Address
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| 244 | ; ZF: Set if CGA Base Port found in BDA
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| 245 | ; Corrupts registers:
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| 246 | ; Nothing
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| 247 | ;--------------------------------------------------------------------
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| 248 | ALIGN JUMP_ALIGN
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| 249 | LoadAndVerifyStatusRegisterFromBDA:
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| 250 | mov dx, [BDA.wVidPort]
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| 251 | add dl, OFFSET_TO_CGA_STATUS_REGISTER
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| 252 | cmp dx, CGA_STATUS_REGISTER
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| 253 | ret
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| 254 |
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| 255 | %endif ; ELIMINATE_CGA_SNOW
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