2017-06-11 14:18:38 +00:00
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# Print Fixed Point #.16 Fraction
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2017-06-11 14:37:51 +00:00
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# Theory
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Printing the fractional value of a 16-bit fixed point number in decimal is rather trivial.
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For example, the number `0.7106` in 16-bit fixed point is 0.71506 * 65536 = 46,569 = `$B5E9`
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How do we convert the number `$B5E9` back into `7106` ? By _digit peeling._
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1. Multipy N by 10
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2. Print the Integer Part digit
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3. Set the Integer Part to zero
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5. Have we printed the number of decimal digits we want? If no then goto step 1
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Example:
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```
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0.7106 * 65536 = $B5E9
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'.'
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$B5E9 * $A = $7.1B1A
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$1B1A * $A = $1.0F04
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$0F04 * $A = $0.9628
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$9628 * $A = $5.DD90
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$5DD9 * $A = $8.A7A0
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0.71058 _______________________^
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```
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An optimization for N*10 is that this is equivalent to: `N*8 + N*2`
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# Application
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## Assembly (Source)
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2017-06-11 14:18:38 +00:00
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See file [print_fract.s](print_fract.s)
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2017-06-11 14:37:51 +00:00
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## Binary (Executable)
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2017-06-11 14:18:38 +00:00
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```
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2017-06-11 14:22:00 +00:00
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CALL-151
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2017-06-11 14:18:38 +00:00
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0800:a2 b5 a0 e9 20 15 08 a2 00 bd 70 08 20 ed fd e8
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0810:e0 05 d0 f5 60 a9 00 8d 6a 08 8e 6b 08 8c 6c 08
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0820:a2 00 20 60 08 20 54 08 20 60 08 20 60 08 20 44
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0830:08 ad 6a 08 09 b0 9d 70 08 a9 00 8d 6a 08 e8 e0
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0840:05 d0 df 60 18 a0 02 b9 6a 08 79 6d 08 99 6a 08
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0850:88 10 f4 60 a0 02 b9 6a 08 99 6d 08 88 10 f7 60
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0860:0e 6c 08 2e 6b 08 2e 6a 08 60 00 00 00 00 00 00
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2017-06-11 14:22:00 +00:00
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0870:00 00 00 00 00
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800G
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2017-06-11 14:18:38 +00:00
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```
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2017-06-11 14:22:00 +00:00
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2017-06-11 14:37:51 +00:00
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## Output
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2017-06-11 14:22:00 +00:00
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```
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2017-06-11 14:37:51 +00:00
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71058
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2017-06-11 14:22:00 +00:00
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```
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