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149 lines
2.8 KiB
149 lines
2.8 KiB
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Converts integer to string
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; IN: eax = number to convert
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; IN: edi = base of string buffer
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; OUT: ecx = number of characters written to buffer
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IntToString:
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push eax
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push esi
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push edx
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push edi
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push ebp
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mov ecx, esi ; store negative original buffer base
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neg ecx ; (used for counting amount of characters)
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test eax, eax
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jns .not_negative
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mov BYTE [esi], '-'
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neg eax
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add esi, 1
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.not_negative:
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mov edi, esi ; store pointer after potential negative sign character
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mov ebp, 0xcccccccd ; ebp = 32 bit multiplicative reciprocal of 10
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.divide_loop:
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mov ebx, eax ; save number in ebx
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mul ebp
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shr edx, 3 ; edx = quotient
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lea eax, [edx + edx*4] ; eax = quotient * 10 = (number - remainder)
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add eax, eax ; |
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sub ebx, eax ; ebx = number - (number - remainder) = remainder
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add ebx, '0' ; remainder is our digit, turn it ASCII
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mov BYTE [esi], bl ; store ASCII digit to buffer
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lea esi, [esi+1]
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mov eax, edx ; We need quotient in eax for 'mul'
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test eax, eax
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jne .divide_loop
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add ecx, esi ; Update amount of characters
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mov byte [esi], 0x00 ; Add null terminator to end of string
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lea esi, [esi-1] ; We incremented the buffer pointer once too much
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.swap_loop:
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cmp edi, esi
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jae .done_swapping
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movzx eax, BYTE [esi]
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movzx edx, BYTE [edi]
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mov BYTE [esi], dl
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mov BYTE [edi], al
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sub esi, 1
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add edi, 1
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jmp .swap_loop
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.done_swapping:
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pop ebp
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pop edi
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pop edx
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pop esi
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pop eax
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ret
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Right justifies source string within the given justification width
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; IN: esi = base of string buffer
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; IN: edx = justification width
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; IN: ecx = string length
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; ASSUMES: that the justification width > string length
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; ASSUMES: that the size of the string buffer > justification width
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RightJustifyString:
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push esi
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push edx
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push ecx
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push eax
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pushfd
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lea esi, [esi + ecx] ; should include null terminator
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lea edi, [esi + edx]
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std
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sub edx, ecx ; edx should be difference
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.copy_loop:
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lodsb ; al = char
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stosb
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sub ecx, 1
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jnz .copy_loop
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; mov al, byte ' '
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; .pad_loop:
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; movsb
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; sub edx, 1
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; jnz .pad_loop
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pushfd
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pop eax
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pop ecx
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pop edx
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pop esi
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ret
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Puts the stringified version of eax on the stack
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; IN: esi = base of string
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; IN: ecx = string length
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; IN: ah = character attributes
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PrintString:
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push ecx
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push eax
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push edi
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push esi
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.print_loop:
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mov al, byte [esi]
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mov word [edi], ax
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lea esi, [esi+1]
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lea edi, [edi+2]
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sub ecx, 1
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jnz .print_loop
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pop esi
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pop edi
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pop eax
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pop ecx
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ret
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