BBC BASIC Programmers' Reference

User Tools

Site Tools

Trace: • converting_20graphics_20coordinates
using_20the_20fscale_20instruction

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

Both sides previous revisionPrevious revision
Next revision		Previous revision
using_20the_20fscale_20instruction [2018/04/01 14:41] – 86.143.37.84using_20the_20fscale_20instruction [2024/01/05 00:21] (current) – external edit 127.0.0.1
Line 1: Line 1:
 =====Using the fscale instruction===== =====Using the fscale instruction=====
  
-//by Tony Tooth, January 2016//\\ \\  Randall Hyde's book "The Art of Assembly Language" omits to cover or even mention the fscale instruction in the main text or in the index, although it is in his Table B-2: Floating Point Instruction Set.\\ \\  fscale (I discovered only late in 2015 - after more than 10 years experience programming in assembly language) is a fast and efficient way to implement the exponential function in assembly language. The way I did this hitherto was incredibly cumbersome. I have written a simple sub-routine in assembly language to illustrate the use of fscale. Note that my illustrative routine does not check for out-of-bounds numbers.\\ \\+//by Tony Tooth, January 2016. Edited by Tony Tooth April 2018//\\ \\  Randall Hyde's book "The Art of Assembly Language" omits to cover or even mention the fscale instruction in the main text or in the index, although it is in his Table B-2: Floating Point Instruction Set.\\ \\  fscale (I discovered only late in 2015 - after more than 10 years experience programming in assembly language) is a fast and efficient way to implement the exponential function in assembly language. The way I did this hitherto was incredibly cumbersome. I have written a simple sub-routine in assembly language to illustrate the use of fscale. Note that my illustrative routine does not check for out-of-bounds numbers.
  
 +<code bb4w> 
       DEF FN_fractpower(num, pow)       DEF FN_fractpower(num, pow)
       LOCAL pass&, res       LOCAL pass&, res
Line 43: Line 44:
  
       = res       = res
 +</code>
  
-\\ //Edit by Richard Russell, January 2016://\\ \\  An alternative way of computing the exponential function in BB4W v6 assembly language is to call the internal EXP routine, which is exposed via the **@fn%()** jump table, as follows (it uses **fscale** internally):\\ \\ +//Edit by Richard Russell, January 2016://\\ \\  An alternative way of computing the exponential function in BB4W v6 assembly language is to call the internal EXP routine, which is exposed via the **@fn%()** jump table, as follows (it uses **fscale** internally): 
 + 
 +<code bb4w> 
         @% = &1415         @% = &1415
         REPEAT         REPEAT
Line 73: Line 77:
         CALL X%         CALL X%
         = y         = y
 +</code>
 +
using_20the_20fscale_20instruction.1522593689.txt.gz · Last modified: 2024/01/05 00:16 (external edit)