annotate code_part1/OSTC_code_asm_part1/math.asm @ 342:06299199dfb9

Fix bad max depth value (fix sub16 to avoid trashing sub_b).
author JeanDo
date Fri, 20 May 2011 01:34:59 +0200
parents 8d6aca08f66b
children cec312042b94
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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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8d6aca08f66b Use signed arithmetic for pressure/temperature compensation.
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19 ; history:
8d6aca08f66b Use signed arithmetic for pressure/temperature compensation.
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20 ; 2005-10-30: Written by Matthias Heinrichs, info@heinrichsweikamp.com
8d6aca08f66b Use signed arithmetic for pressure/temperature compensation.
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21 ; 2007-06-21: MH last updated
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22 ; 2011-01-19: Clean up of isr variante.
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23 ; known bugs:
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24 ; ToDo: clean up!
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25
88
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26
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27 convert_time: ; converts hi:lo in minutes to hours (hi) and minutes (lo)
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28 movff lo,xA+0 ; divide by 60...
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29 movff hi,xA+1 ;
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30 movlw d'60' ;
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31 movwf xB+0 ;
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32 clrf xB+1 ;
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33 rcall div16x16 ; xA/xB=xC with xA as remainder
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34 movff xC+0,hi ; Hours
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35 movff xA+0,lo ; =remaining minutes (0.....59)
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36 return
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37
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38 div16:
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39 ; divA=divA/2^divB (divB: 8Bit only!)
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40 bcf STATUS,C
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41 rrcf divA+1
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42 rrcf divA
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43 decfsz divB
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44 bra div16
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45 return
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46
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47 sub16:
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48 ; sub_c = sub_a - sub_b
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49 bcf neg_flag
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50 movf sub_b+0, W ; Get Value to be subtracted
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51 subwf sub_a+0, W ; Do the High Byte
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52 movwf sub_c+0
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53 movf sub_b+1, W ; Get the Value to be Subbed
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54 subwfb sub_a+1, W
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55 movwf sub_c+1
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56
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57 btfsc STATUS,C
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58 return ; result positve
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59
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60 bsf neg_flag ; result negative
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61
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62 comf sub_c+1 ; 16bit sign change.
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63 negf sub_c+0
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64 btfsc STATUS,C ; Carry to propagate ?
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65 incf sub_c+1,F ; YES: do it.
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66
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67 return
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68
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69 mult16x16: ;xA*xB=xC
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70 clrf xC+2 ; Clear the High-Order Bits
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71 clrf xC+3
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72 movf xA, w ; Do the "L" Multiplication first
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73 mulwf xB
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74 movf PRODL, w ; Save result
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75 movwf xC
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76 movf PRODH, w
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77 movwf xC+1
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78 movf xA, w ; Do the "I" Multiplication
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79 mulwf xB+1
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80 movf PRODL, w ; Save the Most Significant Byte First
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81 addwf xC+1, f
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82 movf PRODH, w
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83 addwfc xC+2, f ; Add to the Last Result
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84 movf xA+1, w ; Do the "O" Multiplication
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85 mulwf xB
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86 movf PRODL, w ; Add the Lower Byte Next
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87 addwf xC+1, f
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88 movf PRODH, w ; Add the High Byte First
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89 addwfc xC+2, f
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90 btfsc STATUS, C ; Add the Carry
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91 incf xC+3, f
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92 movf xA+1, w ; Do the "F" Multiplication
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93 mulwf xB+1
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94 movf PRODL, w
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95 addwf xC+2, f
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96 movf PRODH, w
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97 addwfc xC+3, f
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98 return
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99
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100
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101 div16x16: ;xA/xB=xC with xA as remainder
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102 ;uses divB as temp variable
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103 clrf xC+0
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104 clrf xC+1
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105 MOVF xB+0,W ; Check for zero
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106 IORWF xB+1,W ;
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107 BTFSC STATUS,Z ; Check for zero
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108 RETLW H'FF' ; return 0xFF if illegal
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109 MOVLW 1 ; Start count at 1
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110 MOVWF divB ; Clear Count
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111 div16x16_1
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112 BTFSC xB+1,7 ; High bit set ?
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113 bra div16x16_2 ; Yes then continue
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114 INCF divB,F ; Increment count
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115
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116 bcf STATUS,C
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117 rlcf xB+0,F
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118 rlcf xB+1,F
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119 bra div16x16_1
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120 div16x16_2:
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121 ; Shift result left
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122 bcf STATUS,C
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123 rlcf xC+0,F
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124 rlcf xC+1,F
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125
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126 ; Reduce Divisor
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127
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128 MOVF xB,W ; Get low byte of subtrahend
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129 SUBWF xA,F ; Subtract DST(low) - SRC(low)
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130 MOVF xB+1,W ; Now get high byte of subtrahend
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131 BTFSS STATUS,C ; If there was a borrow, rather than
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132 INCF xB+1,W ; decrement high byte of dst we inc src
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133 SUBWF xA+1,F ; Subtract the high byte and we're done
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134
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135
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136 BTFSC STATUS, C ; Did it reduce?
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137 bra div16x16_3 ; No, so it was less than
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138
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139 movf xB+0,W ; Reverse subtraction
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140 addwf xA+0,F
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141 movf xB+1,W
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142 addwfc xA+1,F
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143
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144 bra div16x16_4 ; Continue the process
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145 div16x16_3:
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146 BSF xC+0,0 ; Yes it did, this gets a 1 bit
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147 div16x16_4:
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148 DECF divB,F ; Decrement N_COUNT
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149 BTFSC STATUS,Z ; If its not zero then continue
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150 return
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151
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152 bcf STATUS,C
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153 rrcf xB+1,F
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154 rrcf xB+0,F
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155
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156 bra div16x16_2 ; Next bit.
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157
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158 div32x16: ; xC:4 / xB:2 = xC+3:xC+2 with xC+1:xC+0 as remainder
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159 ; Setup
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160 movlw .32 ; setup shift counter
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161 movwf divB
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162 movf xC+3,W ; move ACCb to ACCf
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163 movwf xA+1
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164 movf xC+2,W
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165 movwf xA+0
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166 movf xC+1,W ; move ACCc to ACCe
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167 movwf sub_a+1
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168 movf xC+0,W
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169 movwf sub_a+0
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170 clrf xC+3
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171 clrf xC+2
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172 clrf xC+1
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173 clrf xC+0
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174 clrf sub_b+1
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175 clrf sub_b+0
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176 div32x16_2
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177 bcf STATUS,C
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178 rlcf sub_a+0,F
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179 rlcf sub_a+1,F
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180 rlcf xA+0,F
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181 rlcf xA+1,F
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182 rlcf sub_b+0,F
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183 rlcf sub_b+1,F
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184 movf xB+1,W
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185 subwf sub_b+1,W ; check if a>d
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186 btfss STATUS,Z
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187 goto div32x16_3
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188 movf xB+0,W
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189 subwf sub_b+0,W ; if msb equal then check lsb
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190 div32x16_3
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191 btfss STATUS,C ; carry set if d>a
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192 goto div32x16_4
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193 movf xB+0,W ; d-a into d
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194 subwf sub_b+0,F
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195 btfss STATUS,C
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196 decf sub_b+1,F
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197 movf xB+1,W
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198 subwf sub_b+1,F
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199 bsf STATUS,C ; shift a 1 into b (result)
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200 div32x16_4
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201 rlcf xC+0,F
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202 rlcf xC+1,F
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203 rlcf xC+2,F
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204 rlcf xC+3,F
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205 decfsz divB,F ; loop until all bits checked
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206 goto div32x16_2
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207 return
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208
161
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209 ;=============================================================================
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210 ; u16 * u16 --> 32bit multiply (xA * xB --> xC)
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211 ; Used in interupt service routines, to compute temperature and pressure.
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212 ;
0
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213 isr_mult16x16:
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214 clrf isr_xC+2 ; Clear the High-Order Bits
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215 clrf isr_xC+3
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216 movf isr_xA, w ; Do the "L" Multiplication first
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217 mulwf isr_xB
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218 movf PRODL, w ; Save result
161
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219 movwf isr_xC+0
0
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220 movf PRODH, w
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221 movwf isr_xC+1
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222 movf isr_xA+0, w ; Do the "I" Multiplication
0
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223 mulwf isr_xB+1
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224 movf PRODL, w ; Save the Most Significant Byte First
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225 addwf isr_xC+1, f
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226 movf PRODH, w
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227 addwfc isr_xC+2, f ; Add to the Last Result
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228 movf isr_xA+1, w ; Do the "O" Multiplication
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229 mulwf isr_xB
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230 movf PRODL, w ; Add the Lower Byte Next
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231 addwf isr_xC+1, f
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232 movf PRODH, w ; Add the High Byte First
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233 addwfc isr_xC+2, f
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234 btfsc STATUS, C ; Add the Carry
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235 incf isr_xC+3, f
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236 movf isr_xA+1, w ; Do the "F" Multiplication
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237 mulwf isr_xB+1
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238 movf PRODL, w
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239 addwf isr_xC+2, f
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240 movf PRODH, w
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241 addwfc isr_xC+3, f
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242 return
161
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243
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244 ;=============================================================================
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245 ; 24bit shift, repeted WREG times.
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246 ; Because we shift less than 8bits, and keep only C[2:1], we don't care what
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247 ; bit is inserted...
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248 ;
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249 isr_shift_C31:
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250 rrcf isr_xC+3,F ; Shift the three bytes...
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251 rrcf isr_xC+2,F
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252 rrcf isr_xC+1,F
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253 decfsz WREG
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254 bra isr_shift_C31
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255 return
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256
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257 ;=============================================================================
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258 ; s16 * s16 --> 32bit multiply (xA * xB --> xC)
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259 ; Signed multiplication.
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260 ; Code from... the Pic18F documentation ;-)
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261 isr_unsigned_mult16x16:
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262 MOVF isr_xA+0, W ; Lowest is simply a[0] * b[0]
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263 MULWF isr_xB+0
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264 MOVFF PRODL, isr_xC+0
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265 MOVFF PRODH, isr_xC+1
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266 ;
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267 MOVF isr_xA+1, W ; And highest a[1] * b[1]
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268 MULWF isr_xB+1
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269 MOVFF PRODL, isr_xC+2
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270 MOVFF PRODH, isr_xC+3
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271 ;
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272 MOVF isr_xA+0, W ; Intermediates do propagate:
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273 MULWF isr_xB+1
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274 MOVF PRODL, W
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275 ADDWF isr_xC+1, F ; Add cross products
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276 MOVF PRODH, W
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277 ADDWFC isr_xC+2, F ; with propagated carry
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278 CLRF WREG
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279 ADDWFC isr_xC+3, F ; on the three bytes.
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280 ;
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281 MOVF isr_xA+1, W ; And the second one, similarly.
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282 MULWF isr_xB+0
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283 MOVF PRODL, W
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284 ADDWF isr_xC+1, F ; Add cross products
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285 MOVF PRODH, W
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286 ADDWFC isr_xC+2, F
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287 CLRF WREG
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288 ADDWFC isr_xC+3, F
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289 return
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290
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291 isr_signed_mult16x16:
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292 rcall isr_unsigned_mult16x16
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293
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294 ; Manage sign extension of operand B
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295 BTFSS isr_xB+1,7 ; Is B negatif ?
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296 BRA isr_signed_mult_checkA ; No: check ARG1
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297 MOVF isr_xA+0, W ; Yes: add -65536 * A
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298 SUBWF isr_xC+2, F
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299 MOVF isr_xA+1, W
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300 SUBWFB isr_xC+3, F
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301 ; And of operand A
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302 isr_signed_mult_checkA
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303 BTFSS isr_xA+1, 7 ; Is A negatif ?
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304 RETURN ; No: done
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305 MOVF isr_xB+0, W
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306 SUBWF isr_xC+2, F
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307 MOVF isr_xB+1, W
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308 SUBWFB isr_xC+3, F
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309 RETURN