Improve formatting in small terms.

This change does a few things:

 1. Uses .nf and .fi to disable fill during block
 2. Shortens block lines likely to wrap
 3. Moves instruction stack effect to subsection header
This commit is contained in:
~d6 2024-08-05 23:36:21 -04:00 committed by Devine Lu Linvega
parent 5a41189405
commit a405e1c106
1 changed files with 49 additions and 76 deletions

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@ -75,14 +75,18 @@ Regular instructions have a single stack effect which is modified in a predictab
For example the generic effect for \fBADD\fP is ( x y -- x+y ). The eight combinations of modes have the following effects:
\fBADD\fP ( x^ y^ -- x+y^ ) sum two bytes using \fBwst\fP
\fBADDr\fP ( [x^ y^] -- [x+y^] ) sum two bytes using \fBrst\fP
\fBADD2\fP ( x* y* -- x+y* ) sum two shorts using \fBwst\fP
\fBADD2r\fP ( [x* y*] -- [x+y*] ) sum two shorts using \fBrst\fP
\fBADDk\fP ( x^ y^ -- x^ y^ x+y^ ) sum two bytes using \fBwst\fP, retain arguments
\fBADDkr\fP ( [x^ y^] -- [x^ y^ x+y^] ) sum two bytes using \fBrst\fP, retain arguments
\fBADD2k\fP ( x* y* -- x* y* x+y* ) sum two shorts using \fBwst\fP, retain arguments
\fBADD2kr\fP ( [x* y*] -- [x* y* x+y*] ) sum two shorts using \fBrst\fP, retain arguments
.nf
\fBADD\fP ( x^ y^ -- x+y^ ) sum bytes from \fBwst\fP
\fBADDr\fP ( [x^ y^] -- [x+y^] ) sum bytes from \fBrst\fP
\fBADD2\fP ( x* y* -- x+y* ) sum shorts from \fBwst\fP
\fBADD2r\fP ( [x* y*] -- [x+y*] ) sum shorts from \fBrst\fP
\fBADDk\fP ( x^ y^ -- x^ y^ x+y^ ) sum and keep bytes from \fBwst\fP
\fBADDkr\fP ( [x^ y^] -- [x^ y^ x+y^] ) sum and keep bytes from \fBrst\fP
\fBADD2k\fP ( x* y* -- x* y* x+y* ) sum and keep shorts from \fBwst\fP
\fBADD2kr\fP ( [x* y*] -- [x* y* x+y*] ) sum and keep shorts from \fBrst\fP
.fi
Thus for regular instructions writing a "generic" effect (leaving sigils off values whose size depends on \fIshort mode\fP) is sufficient to describe its behavior across all eight variations. Note that some instructions always read values of a fixed size. For example the boolean condition read by \fBJCN\fP is always one byte, no matter what modes are used.
@ -98,77 +102,65 @@ We consider the top of the stack to be the first value of the stack, and count b
.BR
.SS INC
( x -- x+1 )
.SS INC ( x -- x+1 )
Increment the top value of the stack by 1.
Overflow will be truncated, so \fB#ff INC\fP will evaluate to \fB0x00\fP.
.SS POP
( x -- )
.SS POP ( x -- )
Remove the top value of the stack.
\fBPOPk\fP is guaranteed to have no effect (it will not change the stack).
.SS NIP
( x y -- y )
.SS NIP ( x y -- y )
Remove the second value of the stack.
\fBNIPk\fP is guaranteed to have no effect (it will not change the stack).
.SS SWP
( x y -- y x )
.SS SWP ( x y -- y x )
Swap the top two values of the stack.
.SS ROT
( x y z -- y z x )
.SS ROT ( x y z -- y z x )
Rotate the top three values of the stack. The lowest becomes the top and the others are each shifted down one place.
.SS DUP
( x -- x x )
.SS DUP ( x -- x x )
Place a copy of the top value of the stack on top of the stack.
.SS OVR
( x y -- x y x )
.SS OVR ( x y -- x y x )
Place a copy of the second value of the stack on top of the stack.
.SS EQU
( x y -- x==y^ )
.SS EQU ( x y -- x==y^ )
Test whether the top two values of the stack are equal.
Result is guaranteed to be boolean (\fB0x00\fP or \fB0x01\fP).
.SS NEQ
( x y -- x!=y^ )
.SS NEQ ( x y -- x!=y^ )
Test whether the top two values of the stack are not equal.
Result is guaranteed to be boolean (\fB0x00\fP or \fB0x01\fP).
.SS GTH
( x y -- x>y^ )
.SS GTH ( x y -- x>y^ )
Test whether the second value of the stack is greater than the top.
Result is guaranteed to be boolean (\fB0x00\fP or \fB0x01\fP).
.SS LTH
( x y -- x<y^ )
.SS LTH ( x y -- x<y^ )
Test whether the second value of the stack is less than the top.
Result is guaranteed to be boolean (\fB0x00\fP or \fB0x01\fP).
.SS JMP
( x -- ; pc <- x )
.SS JMP ( x -- ; pc <- x )
Jump to a location.
@ -178,15 +170,13 @@ It is common to \fBJMP\fP with boolean bytes (0-1) to handle simple conditionals
@max ( x^ y^ -- max^ ) GTHk JMP SWP POP JMP2r
.SS JCN
( x bool^ -- ; pc <- x if bool )
.SS JCN ( x bool^ -- ; pc <- x if bool )
Jump to a location when a condition is true.
The program counter (\fIpc\fP) is updated when \fIbool\fP is non-zero. When \fIx\fP is a byte, it is treated as relative (\fBpc += x\fP) and when \fIx\fP is a short it is treated as absolute (\fBpc = x\fP).
.SS JSR
( x -- [pc+1*] )
.SS JSR ( x -- [pc+1*] )
Jump to a location, saving a reference to return to.
@ -194,82 +184,69 @@ Stores the next address to execute before unconditionally updating the program c
The saved address will always be a short regardless of \fIshort mode\fP.
.SS STH
( x -- [x] )
.SS STH ( x -- [x] )
Move the top value of the stack to the return stack.
.SS LDZ
( zp^ -- x )
.SS LDZ ( zp^ -- x )
Load data from a zero-page address (\fB0x00 - 0xff\fP).
.SS STZ
( x zp^ -- )
.SS STZ ( x zp^ -- )
Store data at a zero-page address (\fB0x00 - 0xff\fP).
.SS LDR
( rel^ -- x )
.SS LDR ( rel^ -- x )
Load data from a relative address (\fBpc + x\fP).
Note that unlike \fBLDZk\fP and \fBLDAk\fP the \fBLDRk\fP instruction is not very useful, since a relative address is usually only meaningful when run from a particular address (i.e. for a particular \fIpc\fP value).
.SS STR
( x rel^ -- )
.SS STR ( x rel^ -- )
Store data at a relative address (\fBpc + x\fP).
Note that unlike \fBSTZk\fP and \fBSTAk\fP the \fBSTRk\fP instruction is not very useful, since a relative address is usually only meaningful when run from a particular address (i.e. for a particular \fIpc\fP value).
.SS LDA
( abs* -- x )
.SS LDA ( abs* -- x )
Load data from an absolute address (\fB0x0000 - 0xffff\fP).
.SS STA
( x abs* -- )
.SS STA ( x abs* -- )
Store data at an absolute address (\fB0x0000 - 0xffff\fP).
.SS DEI
( dev^ -- x )
.SS DEI ( dev^ -- x )
Read data from a device port (\fB0x00 - 0xff\fP).
Reading from some ports may have an effect on the underlying VM; in other cases it will simply read values from device memory. See Varvara device documentation for more details.
.SS DEO
( x dev^ -- )
.SS DEO ( x dev^ -- )
Write data to a device port (\fB0x00 - 0xff\fP).
Writing to some ports may have an effect on the underlying VM; in other cases it will simply write values to device memory. See Varvara device documentation for more details.
.SS ADD
( x y -- x+y )
.SS ADD ( x y -- x+y )
Add the top two values of the stack.
Overflow will be truncated, so \fB#ff #03 ADD\fP will evaluate to \fB0x02\fP.
.SS SUB
( x y -- x-y )
.SS SUB ( x y -- x-y )
Subtract the top of the stack from the second value of the stack.
Underflow will be truncated, so \fB#01 #03 SUB\fP will evaluate to \fB0xfe\fP.
.SS MUL
( x y -- xy )
.SS MUL ( x y -- xy )
Multiply the top two values of the stack.
Overflow will be truncated, so \fB#11 #11 MUL\fP will evaluate to \fB0x21\fP.
.SS DIV
( x y -- x/y )
.SS DIV ( x y -- x/y )
Divide the second value of the stack by the top of the stack.
@ -281,23 +258,19 @@ Unlike \fBADD\fP, \fBSUB\fP, and \fBMUL\fP, \fBDIV\fP does not behave correctly
There is no \fIremainder\fP instruction, but the phrase \fBDIVk MUL SUB\fP can be used to compute the remainder.
.SS AND
( x y -- x&y )
.SS AND ( x y -- x&y )
Compute the bitwise union of the top two values of the stack.
.SS ORA
( x y -- x|y )
.SS ORA ( x y -- x|y )
Compute the bitwise intersection of the top two values of the stack.
.SS EOR
( x y -- x^y )
.SS EOR ( x y -- x^y )
Compute the bitwise exclusive-or (\fIxor\fP) of the top two values of the stack.
.SS SFT
( x rl^ -- (x>>l)<<r )
.SS SFT ( x rl^ -- (x>>l)<<r )
Compute a bit shift of the second value of the stack; the directions and distances are determined by the top value of the stack.
@ -325,7 +298,7 @@ The "immediate jump" instructions are produced by the assembler. They interpret
\fBJMI\fP ( -- ) jump to \fIaddr\fP unconditionally
\fBJCI\fP ( bool^ -- ) jump to \fIaddr\fP if \fIbool\fP is non-zero
\fBJSI\fP ( -- [pc*] ) jump to \fIaddr\fP saving the current address (\fIpc\fP) on the return stack
\fBJSI\fP ( -- [pc*] ) jump to \fIaddr\fP saving the current address (\fIpc\fP) on \fIrst\fP
(The instruction pointer will be moved forward 2 bytes, past the relative address.)
@ -356,8 +329,8 @@ Literal values can be updated dynamically using store instructions:
.SH SEE ALSO
https://wiki.xxiivv.com/site/uxntal_opcodes.html \fIUxntal Opcodes\fP
https://wiki.xxiivv.com/site/uxntal_syntax.html \fIUxntal Syntax\fP
https://wiki.xxiivv.com/site/uxntal_modes.html \fIUxntal Modes\fP
https://wiki.xxiivv.com/site/uxntal_immediate.html \fIImmediate opcodes\fP
https://wiki.xxiivv.com/site/varvara.html \fIVarvara\fP
https://wiki.xxiivv.com/site/uxntal_opcodes.html \fIUxntal Opcodes\fP
https://wiki.xxiivv.com/site/uxntal_syntax.html \fIUxntal Syntax\fP
https://wiki.xxiivv.com/site/uxntal_modes.html \fIUxntal Modes\fP
https://wiki.xxiivv.com/site/uxntal_immediate.html \fIImmediate opcodes\fP
https://wiki.xxiivv.com/site/varvara.html \fIVarvara\fP