OFW FAQ: Difference between revisions
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wrmsr ( value.low value.high addr -- ) |
wrmsr ( value.low value.high addr -- ) |
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=== How do I enter numbers? |
=== How do I enter numbers? === |
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Typing a number pushes it on the stack. |
Typing a number pushes it on the stack. |
Revision as of 04:23, 30 October 2006
What is Forth stack notation?
The stack effect of a Forth word - i.e. the arguments it pops from the stack and the results is pushes back - is conventionally described as follows:
foo ( a b c -- d e )
means that the word "foo" pops three arguments from the stack (c from the top of stack), and pushes two values back (e on the top).
How do I do x86 I/O port accesses in the ofw interpreter?
pc@ ( port# -- byte ) \ Read from an 8-bit I/O port pw@ ( port# -- word ) \ Read from a 16-bit I/O port pl@ ( port# -- long ) \ Read from a 32-bit I/O port pc! ( byte port# -- ) \ Write to an 8-bit I/O port pw! ( word port# -- ) \ Write to a 16-bit I/O port pl! ( long port# -- ) \ Write to a 32-bit I/O port
c is byte, w is short, l is long.
@ is conventional notation for read, takes port# from stack and leaves value on stack
! is convetnional notation for write, takes port# from top of stack and value from underneath that.
for example: 45 66 pc! writes 0x45 to port 0x66 as a byte
How do I do Geode MSR accesses in the ofw interpreter?
rdmsr ( addr -- value.low value.high ) wrmsr ( value.low value.high addr -- )
How do I enter numbers?
Typing a number pushes it on the stack.
OFW defaults to hex radix. If you want a decimal number, precede it with "d# ", as in "d# 99". You can also say "h# 12ab" if you want to be explicit about the hex radix.
For clarity, you can embed punctuation in numbers. I usually write long hex numbers with a period at position 4, e.g. "c000.2001" so I don't have to count 0's when looking at the number. You can also embed ',' e.g "d# 1,000,000". I usually use comma every third position for decimal numbers.
What does the "p" stand for in I/O access words (e.g. pc@ )?
port
I read some MSR, and "." printed tham as signed. is there a better way to print?
. pops stack and displays signed number in default radix.
u. displays unsigned.
.x or .h displays in hex.
.d displays in decimal.