Difference between revisions of "Forth parser"
From ScienceZero
(Created page with " : lsl for dup + next ; ( Simple complete function that implements left shift by repeated addition ) ":" this tells the parser to define a new function "lsl" is the n...") |
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Revision as of 14:33, 24 April 2018
: lsl for dup + next ; ( Simple complete function that implements left shift by repeated addition )
":" this tells the parser to define a new function
"lsl" is the name of the function
Adr Value
0 0xF0 ( for )
1 0xE0 ( dup )
2 0xC0 ( add )
3 0xF1 ( next )
";" tells the parser that it has reached the end of the definition
The parser should create an "object" in memory like:
"lsl",0xF0,0xE0,0xC0,0xF1
input text --> look up tables --> output binary
How to encode numbers:
if number = 0 then emit LDC #0
else
find the topmost hex digit that is not 0, call it x
emit LDC #x
zero out that digit
for each remaining digit y, zero or not
emit LDE #y
