[2] | 1 | ; File name : math.asm |
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| 2 | ; Project name : Math library |
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| 3 | ; Created date : 7.10.2009 |
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| 4 | ; Last update : 1.1.2010 |
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| 5 | ; Author : Tomi Tilli |
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| 6 | ; Description : ASM library to for math related functions. |
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| 7 | |
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| 8 | ;--------------- Equates ----------------------------- |
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| 9 | |
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| 10 | ; String library function to include |
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| 11 | %define USE_MATH_MULDWBYW ; Math_MulDWbyW |
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| 12 | %define USE_MATH_DIVDWBYW ; Math_DivDWbyW |
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| 13 | %define USE_MATH_REMTOTENTHS ; Math_RemToTenths |
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| 14 | |
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| 15 | |
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| 16 | ;-------------- Private global variables ------------- |
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| 17 | ; Section containing initialized data |
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| 18 | ;SECTION .data |
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| 19 | |
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| 20 | |
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| 21 | ;-------------- Public functions --------------------- |
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| 22 | ; Section containing code |
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| 23 | SECTION .text |
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| 24 | |
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| 25 | |
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| 26 | ;-------------------------------------------------------------------- |
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| 27 | ; Macro to select lesser of two unsigned operands. |
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| 28 | ; |
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| 29 | ; MIN_U |
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| 30 | ; Parameters: |
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| 31 | ; %1: Operand 1 |
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| 32 | ; %2: Operand 2 |
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| 33 | ; Returns: |
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| 34 | ; %1: Lesser unsigned operand |
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| 35 | ; Corrupts registers: |
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| 36 | ; Nothing |
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| 37 | ;-------------------------------------------------------------------- |
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| 38 | %macro MIN_U 2 |
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| 39 | cmp %1, %2 ; Is %1 smaller? |
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| 40 | jb %%Return ; If so, return |
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| 41 | mov %1, %2 ; Copy %2 to %1 |
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| 42 | ALIGN JUMP_ALIGN |
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| 43 | %%Return: |
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| 44 | %endmacro |
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| 45 | |
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| 46 | |
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| 47 | ;-------------------------------------------------------------------- |
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| 48 | ; Macro to select greater of two unsigned operands. |
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| 49 | ; |
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| 50 | ; MAX_U |
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| 51 | ; Parameters: |
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| 52 | ; %1: Operand 1 |
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| 53 | ; %2: Operand 2 |
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| 54 | ; Returns: |
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| 55 | ; %1: Greater unsigned operand |
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| 56 | ; Corrupts registers: |
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| 57 | ; Nothing |
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| 58 | ;-------------------------------------------------------------------- |
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| 59 | %macro MAX_U 2 |
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| 60 | cmp %1, %2 ; Is %1 greater? |
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| 61 | ja %%Return ; If so, return |
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| 62 | mov %1, %2 ; Copy %2 to %1 |
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| 63 | ALIGN JUMP_ALIGN |
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| 64 | %%Return: |
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| 65 | %endmacro |
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| 66 | |
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| 67 | |
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| 68 | ;-------------------------------------------------------------------- |
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| 69 | ; Macro to select lesser and greater of two unsigned operands. |
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| 70 | ; |
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| 71 | ; MINMAX_U |
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| 72 | ; Parameters: |
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| 73 | ; %1: Operand 1 |
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| 74 | ; %2: Operand 2 |
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| 75 | ; Returns: |
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| 76 | ; %1: Lesser unsigned operand |
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| 77 | ; %2: Greater unsigned operand |
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| 78 | ; Corrupts registers: |
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| 79 | ; Nothing |
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| 80 | ;-------------------------------------------------------------------- |
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| 81 | %macro MINMAX_U 2 |
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| 82 | cmp %1, %2 ; Is %1 smaller? |
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| 83 | jbe %%Return ; If so, return |
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| 84 | xchg %1, %2 ; Exchange operands |
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| 85 | ALIGN JUMP_ALIGN |
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| 86 | %%Return: |
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| 87 | %endmacro |
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| 88 | |
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| 89 | |
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| 90 | ;-------------------------------------------------------------------- |
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| 91 | ; DWORD * WORD multiplication. |
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| 92 | ; Multiplies unsigned 32-bit integer by unsigned 16-bit integer. |
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| 93 | ; Result is unsigned 32-bit integer, so overflow is possible. |
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| 94 | ; |
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| 95 | ; Math_MulDWbyW |
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| 96 | ; Parameters: |
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| 97 | ; DX:AX: 32-bit unsigned integer to multiply |
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| 98 | ; CX: 16-bit unsigned multiplier |
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| 99 | ; Returns: |
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| 100 | ; DX:AX: 32-bit unsigned integer |
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| 101 | ; Corrupts registers: |
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| 102 | ; Nothing |
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| 103 | ;-------------------------------------------------------------------- |
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| 104 | %ifdef USE_MATH_MULDWBYW |
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| 105 | ALIGN JUMP_ALIGN |
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| 106 | Math_MulDWbyW: |
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| 107 | jcxz .RetZero ; If CX=0, return 0 |
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| 108 | push bx |
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| 109 | mov bx, dx ; Copy hiword to BX |
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| 110 | xor dx, dx ; Zero DX for multiplication |
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| 111 | mul cx ; DX:AX = AX (loword) * CX (multiplier) |
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| 112 | push dx ; Push possible overflow |
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| 113 | xchg ax, bx ; => AX=old hiword, BX=new loword |
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| 114 | xor dx, dx ; Zero DX for division |
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| 115 | mul cx ; DX:AX = AX (hiword) * CX (multiplier) |
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| 116 | pop dx ; Pop possible overflow from first mul |
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| 117 | add dx, ax ; Add new hiword to overflow from first mul |
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| 118 | mov ax, bx ; Copy new loword to AX |
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| 119 | pop bx |
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| 120 | ret |
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| 121 | ALIGN JUMP_ALIGN |
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| 122 | .RetZero: ; Return 0 in DX:AX |
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| 123 | xor ax, ax |
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| 124 | xor dx, dx |
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| 125 | ret |
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| 126 | %endif |
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| 127 | |
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| 128 | |
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| 129 | ;-------------------------------------------------------------------- |
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| 130 | ; Divide a 32-bit unsigned integer so that quotient can be 32-bit. |
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| 131 | ; |
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| 132 | ; Math_DivDWbyW |
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| 133 | ; Parameters: |
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| 134 | ; DX:AX: 32-bit unsigned divident |
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| 135 | ; CX: 16-bit unsigned divisor |
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| 136 | ; Returns: |
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| 137 | ; DX:AX: 32-bit unsigned quotient |
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| 138 | ; BX: 16-bit unsigned remainder |
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| 139 | ; Corrupts registers: |
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| 140 | ; Nothing |
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| 141 | ;-------------------------------------------------------------------- |
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| 142 | %ifdef USE_MATH_DIVDWBYW |
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| 143 | ALIGN JUMP_ALIGN |
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| 144 | Math_DivDWbyW: |
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| 145 | mov bx, ax |
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| 146 | mov ax, dx |
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| 147 | xor dx, dx |
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| 148 | div cx |
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| 149 | xchg ax, bx |
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| 150 | div cx |
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| 151 | xchg dx, bx |
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| 152 | ret |
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| 153 | %endif |
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| 154 | |
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| 155 | |
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| 156 | ;-------------------------------------------------------------------- |
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| 157 | ; Converts remainder to tenths. |
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| 158 | ; |
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| 159 | ; Math_RemToTenths |
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| 160 | ; Parameters: |
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| 161 | ; BX: 16-bit unsigned remainder |
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| 162 | ; CX: 16-bit unsigned divisor used when calculated the remainder (max 2559) |
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| 163 | ; Returns: |
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| 164 | ; BX: Remainder converted to tenths |
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| 165 | ; Corrupts registers: |
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| 166 | ; Nothing |
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| 167 | ;-------------------------------------------------------------------- |
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| 168 | %ifdef USE_MATH_REMTOTENTHS |
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| 169 | ALIGN JUMP_ALIGN |
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| 170 | Math_RemToTenths: |
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| 171 | push cx |
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| 172 | push ax |
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| 173 | mov ax, cx ; Copy divisor to AX |
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| 174 | mov cl, 10 ; Load 10 to CL |
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| 175 | div cl ; AL = Divisor divided by 10 |
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| 176 | inc ax ; Increment to compensate new remainder |
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| 177 | xchg ax, bx ; AX = 16-bit remainder to convert |
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| 178 | ; BL = Original divisor divided by 10 |
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| 179 | div bl ; AX = Original remainder converted to tenths |
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| 180 | eMOVZX bx, al ; Copy return value to BX |
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| 181 | pop ax |
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| 182 | pop cx |
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| 183 | ret |
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| 184 | %endif |
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