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Index > Windows > Creating a constant float from a string

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NanoBytes



Joined: 02 Jun 2011
Posts: 57
Location: Iowa, United States
NanoBytes
Hey guys, I realize that what I am asking is daunting and fairly complex (As I have learned from the past week or so). I am trying to create a procedure that will alow me to simulate a constant float throught the use of strings
Code:
stdcall makeFloat, "3.21"    

The process that I was is as follows: first read the integral part of the string, which is "3", load it into the floating point stack, then read the decimal part and add it onto the integral part of the number. Well, this is all theoretical, the task was to complex for me to create a working process, and I was woundering if you guys could help me. My issue is with the decimal part, this part needs to be read backwards, meaning that you start reading from the end of the string and move tward the begining. Here is an example
Code:
Value = (1)+Value*0.1 = 1.0
Value = (2)+Value*0.1 = 2.1
Value = Value*0.1 = 0.21
    

The numbers in parenthesis are the numbers read from the string. After the loop is over you would, in theory, add the value onto the integer value previosly read. Like I said, the task is complex, could any of you provide me with a procedure that will do this, or al least the floating point part of the string. Confused

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Post 02 Oct 2011, 18:24
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Quote:

My issue is with the decimal part, this part needs to be read backwards
Why is that? Wouldn't the following pseudo-code do the work as well?
Code:
num= load_integer_part()
divisor = 10.0
for each fractional digit in forward direction do
  num = num + ascii_to_float(digit) / divisor
  divisor = divisor * 10
od    
I don't guarantee high quality conversions though, check fasm's sources to get a better implementation.
Post 02 Oct 2011, 18:56
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NanoBytes



Joined: 02 Jun 2011
Posts: 57
Location: Iowa, United States
NanoBytes
Hmmm, I like that, much simpler than I presumed, thanks, Ill try it Smile
Post 02 Oct 2011, 20:22
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bitRAKE



Joined: 21 Jul 2003
Posts: 3043
Location: vpcmipstrm
bitRAKE
Using FBLD / FBSTP would be an easy lesser alternative. Multiple digits can be converted simultaneously and then a single division used to scale integer based on decimal point.

http://www.website.masmforum.com/tutorials/fptute/fpuchap6.htm
Post 02 Oct 2011, 20:25
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