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1 ; OSTC - diving computer code
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2 ; Copyright (C) 2008 HeinrichsWeikamp GbR
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3
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4 ; This program is free software: you can redistribute it and/or modify
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5 ; it under the terms of the GNU General Public License as published by
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6 ; the Free Software Foundation, either version 3 of the License, or
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7 ; (at your option) any later version.
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8
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9 ; This program is distributed in the hope that it will be useful,
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10 ; but WITHOUT ANY WARRANTY; without even the implied warranty of
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11 ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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12 ; GNU General Public License for more details.
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13
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14 ; You should have received a copy of the GNU General Public License
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15 ; along with this program. If not, see <http://www.gnu.org/licenses/>.
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16
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17
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18 ; Math routines
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19 ; written by: Matthias Heinrichs, info@heinrichsweikamp.com
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20 ; written: 10/30/05
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21 ; last updated: 06/21/07
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22 ; known bugs:
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23 ; ToDo: clean up!
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24
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25 convert_time: ; converts hi:lo in minutes to hours (hi) and minutes (lo)
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26 movff lo,xA+0 ; divide by 60...
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27 movff hi,xA+1 ;
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28 movlw d'60' ;
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29 movwf xB+0 ;
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30 clrf xB+1 ;
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31 rcall div16x16 ; xA/xB=xC with xA as remainder
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32 movff xC+0,hi ; Hours
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33 movff xA+0,lo ; =remaining minutes (0.....59)
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34 return
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35
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36 div16:
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37 ; divA=divA/2^divB (divB: 8Bit only!)
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38 bcf STATUS,C
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39 rrcf divA+1
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40 rrcf divA
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41 decfsz divB
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42 bra div16
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43 return
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44
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45 div32:
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46 ; xC=xC(32Bit)/2^divB (divB: 8Bit only!)
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47 bcf STATUS,C
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48 rrcf xC+3
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49 rrcf xC+2
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50 rrcf xC+1
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51 rrcf xC+0
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52 decfsz divB
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53 bra div32
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54 return
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55
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56 invert_xC:
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57 movf xC+1, w ; inverses xC+0:xC+1
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58 sublw 0xFF
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59 movwf xC+1
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60 movf xC+0, w
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61 bcf STATUS,C
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62 sublw 0xFF
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63 movwf xC+0
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64 return
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65
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66
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67 sub16:
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68 ; sub_c = sub_a - sub_b
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69 bcf neg_flag
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70 movf sub_b+0, w ; Get Value to be subtracted
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71 subwf sub_a+0, w ; Do the High Byte
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72 movwf sub_c+0
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73 movf sub_b+1, w ; Get the Value to be Subbed
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74 subwfb sub_a+1, w
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75 movwf sub_c+1
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76 btfss STATUS,N
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77 return ; result positve
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78 ; sub_c = sub_a - sub_b
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79 bsf neg_flag ; result negative
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80 movff sub_c+0,sub_b+0
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81 movff sub_c+1,sub_b+1
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82 setf sub_a
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83 setf sub_a+1
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84 movf sub_b+0, w ; Get Value to be subtracted
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85 subwf sub_a+0, w ; Do the High Byte
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86 movwf sub_c+0
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87 movf sub_b+1, w ; Get the Value to be Subbed
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88 subwfb sub_a+1, w
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89 movwf sub_c+1
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90 return
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91
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92
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93 mult16x16:
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94 ;xA*xB=xC
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95 clrf xC+2 ; Clear the High-Order Bits
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96 clrf xC+3
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97 movf xA, w ; Do the "L" Multiplication first
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98 mulwf xB
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99 movf PRODL, w ; Save result
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100 movwf xC
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101 movf PRODH, w
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102 movwf xC+1
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103 movf xA, w ; Do the "I" Multiplication
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104 mulwf xB+1
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105 movf PRODL, w ; Save the Most Significant Byte First
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106 addwf xC+1, f
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107 movf PRODH, w
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108 addwfc xC+2, f ; Add to the Last Result
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109 movf xA+1, w ; Do the "O" Multiplication
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110 mulwf xB
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111 movf PRODL, w ; Add the Lower Byte Next
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112 addwf xC+1, f
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113 movf PRODH, w ; Add the High Byte First
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114 addwfc xC+2, f
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115 btfsc STATUS, C ; Add the Carry
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116 incf xC+3, f
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117 movf xA+1, w ; Do the "F" Multiplication
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118 mulwf xB+1
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119 movf PRODL, w
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120 addwf xC+2, f
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121 movf PRODH, w
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122 addwfc xC+3, f
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123 return
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124
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125
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126 div16x16: ;xA/xB=xC with xA as remainder
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127 ;uses divB as temp variable
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128 clrf xC+0
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129 clrf xC+1
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130 MOVF xB+0,W ; Check for zero
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131 IORWF xB+1,W ;
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132 BTFSC STATUS,Z ; Check for zero
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133 RETLW H'FF' ; return 0xFF if illegal
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134 MOVLW 1 ; Start count at 1
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135 MOVWF divB ; Clear Count
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136 div16x16_1
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137 BTFSC xB+1,7 ; High bit set ?
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138 bra div16x16_2 ; Yes then continue
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139 INCF divB,F ; Increment count
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140
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141 bcf STATUS,C
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142 rlcf xB+0,F
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143 rlcf xB+1,F
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144 bra div16x16_1
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145 div16x16_2:
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146 ; Shift result left
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147 bcf STATUS,C
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148 rlcf xC+0,F
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149 rlcf xC+1,F
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150
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151 ; Reduce Divisor
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152
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153 MOVF xB,W ; Get low byte of subtrahend
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154 SUBWF xA,F ; Subtract DST(low) - SRC(low)
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155 MOVF xB+1,W ; Now get high byte of subtrahend
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156 BTFSS STATUS,C ; If there was a borrow, rather than
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157 INCF xB+1,W ; decrement high byte of dst we inc src
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158 SUBWF xA+1,F ; Subtract the high byte and we're done
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159
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160
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161 BTFSC STATUS, C ; Did it reduce?
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162 bra div16x16_3 ; No, so it was less than
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163
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164 movf xB+0,W ; Reverse subtraction
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165 addwf xA+0,F
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166 movf xB+1,W
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167 addwfc xA+1,F
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168
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169 bra div16x16_4 ; Continue the process
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170 div16x16_3:
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171 BSF xC+0,0 ; Yes it did, this gets a 1 bit
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172 div16x16_4:
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173 DECF divB,F ; Decrement N_COUNT
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174 BTFSC STATUS,Z ; If its not zero then continue
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175 return
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176
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177 bcf STATUS,C
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178 rrcf xB+1,F
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179 rrcf xB+0,F
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180
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181 bra div16x16_2 ; Next bit.
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182
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183 div32x16: ; xC:4 / xB:2 = xC+3:xC+2 with xC+1:xC+0 as remainder
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184 ; Setup
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185 movlw .32 ; setup shift counter
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186 movwf divB
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187 movf xC+3,W ; move ACCb to ACCf
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188 movwf xA+1
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189 movf xC+2,W
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190 movwf xA+0
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191 movf xC+1,W ; move ACCc to ACCe
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192 movwf sub_a+1
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193 movf xC+0,W
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194 movwf sub_a+0
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195 clrf xC+3
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196 clrf xC+2
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197 clrf xC+1
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198 clrf xC+0
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199 clrf sub_b+1
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200 clrf sub_b+0
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201 div32x16_2
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202 bcf STATUS,C
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203 rlcf sub_a+0,F
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204 rlcf sub_a+1,F
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205 rlcf xA+0,F
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206 rlcf xA+1,F
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207 rlcf sub_b+0,F
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208 rlcf sub_b+1,F
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209 movf xB+1,W
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210 subwf sub_b+1,W ; check if a>d
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211 btfss STATUS,Z
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212 goto div32x16_3
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213 movf xB+0,W
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214 subwf sub_b+0,W ; if msb equal then check lsb
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215 div32x16_3
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216 btfss STATUS,C ; carry set if d>a
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217 goto div32x16_4
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218 movf xB+0,W ; d-a into d
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219 subwf sub_b+0,F
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220 btfss STATUS,C
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221 decf sub_b+1,F
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222 movf xB+1,W
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223 subwf sub_b+1,F
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224 bsf STATUS,C ; shift a 1 into b (result)
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225 div32x16_4
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226 rlcf xC+0,F
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227 rlcf xC+1,F
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228 rlcf xC+2,F
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229 rlcf xC+3,F
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230 decfsz divB,F ; loop until all bits checked
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231 goto div32x16_2
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232 return
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233
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234
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235 isr_div16:
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236 ; divA=divA/2^divB (divB: 8Bit only!)
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237 bcf STATUS,C
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238 rrcf isr_divA+1
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239 rrcf isr_divA
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240 decfsz isr_divB
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241 bra isr_div16
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242 return
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243
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244 isr_div32:
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245 ; xC=xC(32Bit)/2^divB (divB: 8Bit only!)
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246 bcf STATUS,C
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247 rrcf isr_xC+3
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248 rrcf isr_xC+2
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249 rrcf isr_xC+1
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250 rrcf isr_xC+0
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251 decfsz isr_divB
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252 bra isr_div32
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253 return
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254
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255 isr_invert_xC:
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256 movf isr_xC+1, w ; inverses xC+0:xC+1
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257 sublw 0xFF
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258 movwf isr_xC+1
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259 movf isr_xC+0, w
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260 bcf STATUS,C
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261 sublw 0xFF
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262 movwf isr_xC+0
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263 return
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264
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265
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266 isr_sub16:
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267 ; sub_c = sub_a - sub_b
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268 bcf neg_flag_isr
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269 movf isr_sub_b+0, w ; Get Value to be subtracted
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270 subwf isr_sub_a+0, w ; Do the High Byte
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271 movwf isr_sub_c+0
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272 movf isr_sub_b+1, w ; Get the Value to be Subbed
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273 subwfb isr_sub_a+1, w
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274 movwf isr_sub_c+1
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275 btfss STATUS,N
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276 return ; result positve
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277 ; sub_c = sub_a - sub_b
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278 bsf neg_flag_isr ; result negative
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279 movff isr_sub_c+0,isr_sub_b+0
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280 movff isr_sub_c+1,isr_sub_b+1
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281 setf isr_sub_a
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282 setf isr_sub_a+1
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283 movf isr_sub_b+0, w ; Get Value to be subtracted
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284 subwf isr_sub_a+0, w ; Do the High Byte
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285 movwf isr_sub_c+0
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286 movf isr_sub_b+1, w ; Get the Value to be Subbed
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287 subwfb isr_sub_a+1, w
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288 movwf isr_sub_c+1
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289 return
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290
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291
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292 isr_mult16x16:
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293 ;xA*xB=xC
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294 clrf isr_xC+2 ; Clear the High-Order Bits
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295 clrf isr_xC+3
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296 movf isr_xA, w ; Do the "L" Multiplication first
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297 mulwf isr_xB
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298 movf PRODL, w ; Save result
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299 movwf isr_xC
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300 movf PRODH, w
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301 movwf isr_xC+1
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302 movf isr_xA, w ; Do the "I" Multiplication
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303 mulwf isr_xB+1
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304 movf PRODL, w ; Save the Most Significant Byte First
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305 addwf isr_xC+1, f
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306 movf PRODH, w
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307 addwfc isr_xC+2, f ; Add to the Last Result
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308 movf isr_xA+1, w ; Do the "O" Multiplication
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309 mulwf isr_xB
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310 movf PRODL, w ; Add the Lower Byte Next
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311 addwf isr_xC+1, f
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312 movf PRODH, w ; Add the High Byte First
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313 addwfc isr_xC+2, f
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314 btfsc STATUS, C ; Add the Carry
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315 incf isr_xC+3, f
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316 movf isr_xA+1, w ; Do the "F" Multiplication
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317 mulwf isr_xB+1
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318 movf PRODL, w
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319 addwf isr_xC+2, f
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320 movf PRODH, w
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321 addwfc isr_xC+3, f
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322 return
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323 |
