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1 ;=============================================================================
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2 ;
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3 ; File math.asm
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4 ;
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5 ; Math subroutines
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6 ;
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7 ; Copyright (c) 2011, JD Gascuel, HeinrichsWeikamp, all right reserved.
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8 ;=============================================================================
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9 ; HISTORY
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10 ; 2011-08-03 : [mH] moving from OSTC code
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11
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12
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13 #include "ostc3.inc" ; Mandatory header
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14
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15 basic CODE
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16 ;=============================================================================
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17 global convert_time
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18 convert_time: ; converts hi:lo in minutes to hours (hi) and minutes (lo)
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19 movff lo,xA+0 ; divide by 60...
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20 movff hi,xA+1 ;
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21 movlw d'60' ;
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22 movwf xB+0 ;
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23 clrf xB+1 ;
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24 rcall div16x16 ; xA/xB=xC with xA as remainder
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25 movff xC+0,hi ; Hours
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26 movff xA+0,lo ; =remaining minutes (0.....59)
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27 return
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28
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29 global div16
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30 div16:
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31 ; divA=divA/2^divB (divB: 8Bit only!)
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32 bcf STATUS,C
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33 rrcf divA+1
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34 rrcf divA+0
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35 decfsz divB
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36 bra div16
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37 return
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38
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39 global sub16
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40 sub16:
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41 ; sub_c = sub_a - sub_b (with signed values)
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42 bcf neg_flag
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43 movf sub_b+0, W ; Get Value to be subtracted
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44 subwf sub_a+0, W ; Do the High Byte
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45 movwf sub_c+0
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46 movf sub_b+1, W ; Get the Value to be Subbed
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47 subwfb sub_a+1, W
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48 movwf sub_c+1
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49
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50 btfss STATUS,N ; Negativ result ?
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51 return ; NO: result positive done.
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52
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53 bsf neg_flag ; MARK result negative
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54
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55 comf sub_c+1 ; 16bit sign change.
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56 negf sub_c+0
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57 btfsc STATUS,C ; Carry to propagate ?
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58 incf sub_c+1,F ; YES: do it.
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59
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60 return
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61
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62 global subU16
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63 subU16:
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64 ; sub_c = sub_a - sub_b (with UNSIGNED values)
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65 bcf neg_flag
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66 movf sub_b+0, W ; Get Value to be subtracted
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67 subwf sub_a+0, W ; Do the High Byte
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68 movwf sub_c+0
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69 movf sub_b+1, W ; Get the Value to be Subbed
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70 subwfb sub_a+1, W
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71 movwf sub_c+1
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72 btfsc STATUS,C ; Borrow to propagate ? (B == /CARRY)
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73 return ; NO: result positive done.
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74 bsf neg_flag ; MARK result negative
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75 comf sub_c+1 ; 16bit sign change.
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76 negf sub_c+0
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77 btfsc STATUS,C ; Carry to propagate ?
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78 incf sub_c+1,F ; YES: do it.
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79 return
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80
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81 global mult16x16
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82 mult16x16: ;xA*xB=xC
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83 clrf xC+2 ; Clear the High-Order Bits
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84 clrf xC+3
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85 movf xA, w ; Do the "L" Multiplication first
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86 mulwf xB
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87 movf PRODL, w ; Save result
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88 movwf xC
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89 movf PRODH, w
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90 movwf xC+1
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91 movf xA, w ; Do the "I" Multiplication
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92 mulwf xB+1
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93 movf PRODL, w ; Save the Most Significant Byte First
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94 addwf xC+1, f
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95 movf PRODH, w
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96 addwfc xC+2, f ; Add to the Last Result
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97 movf xA+1, w ; Do the "O" Multiplication
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98 mulwf xB
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99 movf PRODL, w ; Add the Lower Byte Next
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100 addwf xC+1, f
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101 movf PRODH, w ; Add the High Byte First
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102 addwfc xC+2, f
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103 btfsc STATUS, C ; Add the Carry
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104 incf xC+3, f
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105 movf xA+1, w ; Do the "F" Multiplication
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106 mulwf xB+1
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107 movf PRODL, w
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108 addwf xC+2, f
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109 movf PRODH, w
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110 addwfc xC+3, f
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111 return
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112
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113 global div16x16
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114 div16x16: ;xA/xB=xC with xA+0 as remainder
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115 ;uses divB as temp variable
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116 clrf xC+0
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117 clrf xC+1
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118 MOVF xB+0,W ; Check for zero
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119 IORWF xB+1,W ;
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120 BTFSC STATUS,Z ; Check for zero
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121 RETLW H'FF' ; return 0xFF if illegal
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122 MOVLW 1 ; Start count at 1
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123 MOVWF divB ; Clear Count
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124 div16x16_1:
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125 BTFSC xB+1,7 ; High bit set ?
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126 bra div16x16_2 ; Yes then continue
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127 INCF divB,F ; Increment count
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128
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129 bcf STATUS,C
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130 rlcf xB+0,F
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131 rlcf xB+1,F
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132 bra div16x16_1
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133 div16x16_2:
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134 ; Shift result left
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135 bcf STATUS,C
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136 rlcf xC+0,F
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137 rlcf xC+1,F
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138
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139 ; Reduce Divisor
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140
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141 MOVF xB,W ; Get low byte of subtrahend
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142 SUBWF xA,F ; Subtract DST(low) - SRC(low)
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143 MOVF xB+1,W ; Now get high byte of subtrahend
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144 BTFSS STATUS,C ; If there was a borrow, rather than
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145 INCF xB+1,W ; decrement high byte of dst we inc src
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146 SUBWF xA+1,F ; Subtract the high byte and we're done
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147
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148
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149 BTFSC STATUS, C ; Did it reduce?
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150 bra div16x16_3 ; No, so it was less than
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151
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152 movf xB+0,W ; Reverse subtraction
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153 addwf xA+0,F
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154 movf xB+1,W
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155 addwfc xA+1,F
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156
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157 bra div16x16_4 ; Continue the process
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158 div16x16_3:
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159 BSF xC+0,0 ; Yes it did, this gets a 1 bit
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160 div16x16_4:
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161 DECF divB,F ; Decrement N_COUNT
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162 BTFSC STATUS,Z ; If its not zero then continue
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163 return
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164
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165 bcf STATUS,C
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166 rrcf xB+1,F
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167 rrcf xB+0,F
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168
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169 bra div16x16_2 ; Next bit.
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170
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171 global div32x16
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172 div32x16: ; xC:4 / xB:2 = xC+3:xC+2 with xC+1:xC+0 as remainder
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173 ; Setup
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174 movlw .32 ; setup shift counter
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175 movwf divB
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176 movff xC+3,xA+1 ; move ACCb to ACCf
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177 movff xC+2,xA+0
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178 movff xC+1,sub_a+1 ; move ACCc to ACCe
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179 movff xC+0,sub_a+0
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180 clrf xC+3
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181 clrf xC+2
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182 clrf xC+1
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183 clrf xC+0
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184 clrf sub_b+1
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185 clrf sub_b+0
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186 div32x16_2:
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187 bcf STATUS,C
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188 rlcf sub_a+0,F
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189 rlcf sub_a+1,F
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190 rlcf xA+0,F
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191 rlcf xA+1,F
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192 rlcf sub_b+0,F
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193 rlcf sub_b+1,F
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194 movf xB+1,W
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195 subwf sub_b+1,W ; check if a>d
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196 btfss STATUS,Z
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197 bra div32x16_3
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198 movf xB+0,W
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199 subwf sub_b+0,W ; if msb equal then check lsb
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200 div32x16_3:
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201 btfss STATUS,C ; carry set if d>a
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202 bra div32x16_4
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203 movf xB+0,W ; d-a into d
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204 subwf sub_b+0,F
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205 btfss STATUS,C
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206 decf sub_b+1,F
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207 movf xB+1,W
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208 subwf sub_b+1,F
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209 bsf STATUS,C ; shift a 1 into b (result)
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210 div32x16_4:
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211 rlcf xC+0,F
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212 rlcf xC+1,F
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213 rlcf xC+2,F
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214 rlcf xC+3,F
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215 decfsz divB,F ; loop until all bits checked
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216 bra div32x16_2
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217 return
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218
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219 ;;=============================================================================
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220 ;; u16 * u16 --> 32bit multiply (xA * xB --> xC)
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221 ;; Used in interupt service routines, to compute temperature and pressure.
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222 ;;
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223 ; global isr_mult16x16
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224 ;isr_mult16x16:
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225 ; clrf isr_xC+2 ; Clear the High-Order Bits
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226 ; clrf isr_xC+3
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227 ; movf isr_xA, w ; Do the "L" Multiplication first
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228 ; mulwf isr_xB
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229 ; movf PRODL, w ; Save result
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230 ; movwf isr_xC+0
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231 ; movf PRODH, w
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232 ; movwf isr_xC+1
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233 ; movf isr_xA+0, w ; Do the "I" Multiplication
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234 ; mulwf isr_xB+1
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235 ; movf PRODL, w ; Save the Most Significant Byte First
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236 ; addwf isr_xC+1, f
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237 ; movf PRODH, w
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238 ; addwfc isr_xC+2, f ; Add to the Last Result
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239 ; movf isr_xA+1, w ; Do the "O" Multiplication
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240 ; mulwf isr_xB
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241 ; movf PRODL, w ; Add the Lower Byte Next
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242 ; addwf isr_xC+1, f
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243 ; movf PRODH, w ; Add the High Byte First
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244 ; addwfc isr_xC+2, f
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245 ; btfsc STATUS, C ; Add the Carry
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246 ; incf isr_xC+3, f
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247 ; movf isr_xA+1, w ; Do the "F" Multiplication
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248 ; mulwf isr_xB+1
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249 ; movf PRODL, w
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250 ; addwf isr_xC+2, f
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251 ; movf PRODH, w
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252 ; addwfc isr_xC+3, f
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253 ; return
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254
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255 ;=============================================================================
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256 ; 24bit shift, repeted WREG times.
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257 ; Because we shift less than 8bits, and keep only C[2:1], we don't care what
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258 ; bit is inserted...
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259 ;
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260 global isr_shift_C31
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261 isr_shift_C31:
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262 rrcf isr_xC+3,F ; Shift the three bytes...
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263 rrcf isr_xC+2,F
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264 rrcf isr_xC+1,F
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265 decfsz WREG
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266 bra isr_shift_C31
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267 return
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268
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269 ;=============================================================================
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270 ; s16 * s16 --> 32bit multiply (xA * xB --> xC)
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271 ; Signed multiplication.
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272 ; Code from... the Pic18F documentation ;-)
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273 global isr_unsigned_mult16x16
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274 isr_unsigned_mult16x16:
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275 MOVF isr_xA+0, W ; Lowest is simply a[0] * b[0]
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276 MULWF isr_xB+0
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277 MOVFF PRODL, isr_xC+0
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278 MOVFF PRODH, isr_xC+1
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279 ;
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280 MOVF isr_xA+1, W ; And highest a[1] * b[1]
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281 MULWF isr_xB+1
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282 MOVFF PRODL, isr_xC+2
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283 MOVFF PRODH, isr_xC+3
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284 ;
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285 MOVF isr_xA+0, W ; Intermediates do propagate:
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286 MULWF isr_xB+1
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287 MOVF PRODL, W
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288 ADDWF isr_xC+1, F ; Add cross products
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289 MOVF PRODH, W
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290 ADDWFC isr_xC+2, F ; with propagated carry
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291 CLRF WREG
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292 ADDWFC isr_xC+3, F ; on the three bytes.
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293 ;
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294 MOVF isr_xA+1, W ; And the second one, similarly.
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295 MULWF isr_xB+0
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296 MOVF PRODL, W
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297 ADDWF isr_xC+1, F ; Add cross products
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298 MOVF PRODH, W
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299 ADDWFC isr_xC+2, F
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300 CLRF WREG
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301 ADDWFC isr_xC+3, F
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302 return
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303
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304 global isr_signed_mult16x16
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305 isr_signed_mult16x16:
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306 rcall isr_unsigned_mult16x16
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307
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308 ; Manage sign extension of operand B
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309 BTFSS isr_xB+1,7 ; Is B negatif ?
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310 BRA isr_signed_mult_checkA ; No: check ARG1
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311 MOVF isr_xA+0, W ; Yes: add -65536 * A
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312 SUBWF isr_xC+2, F
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313 MOVF isr_xA+1, W
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314 SUBWFB isr_xC+3, F
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315 ; And of operand A
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316 isr_signed_mult_checkA
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317 BTFSS isr_xA+1, 7 ; Is A negatif ?
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318 RETURN ; No: done
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319 MOVF isr_xB+0, W
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320 SUBWF isr_xC+2, F
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321 MOVF isr_xB+1, W
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322 SUBWFB isr_xC+3, F
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323 RETURN
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324
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325 END |
