path: root/doc/Changes

Change log for NASM
===================

This is the Changelog for the official releases; this is a modified
version.  For the changes from the official release, see the MODIFIED file.

0.90 released October 1996
--------------------------

First release version. First support for object file output. Other
changes from previous version (0.3x) too numerous to document.

0.91 released November 1996
---------------------------

Loads of bug fixes.
Support for RDF added.
Support for DBG debugging format added.
Support for 32-bit extensions to Microsoft OBJ format added.
Revised for Borland C: some variable names changed, makefile added.
LCC support revised to actually work.
JMP/CALL NEAR/FAR notation added.
`a16', `o16', `a32' and `o32' prefixes added.
Range checking on short jumps implemented.
MMX instruction support added.
Negative floating point constant support added.
Memory handling improved to bypass 64K barrier under DOS.
$ prefix to force treatment of reserved words as identifiers added.
Default-size mechanism for object formats added.
Compile-time configurability added.
`#', `@', `~' and `?' are now valid characters in labels.
`-e' and `-k' options in NDISASM added.

0.92 released January 1997
--------------------------

The FDIVP/FDIVRP and FSUBP/FSUBRP pairs had been inverted: this was
fixed. This also affected the LCC driver.

Fixed a bug regarding 32-bit effective addresses of the form
[other_register+ESP].

Documentary changes, notably documentation of the fact that Borland
Win32 compilers use `obj' rather than `win32' object format.

Fixed the COMENT record in OBJ files, which was formatted
incorrectly.

Fixed a bug causing segfaults in large RDF files.

OBJ format now strips initial periods from segment and group
definitions, in order to avoid complications with the local label
syntax.

Fixed a bug in disassembling far calls and jumps in NDISASM.

Added support for user-defined sections in COFF and ELF files.

Compiled the DOS binaries with a sensible amount of stack, to
prevent stack overflows on any arithmetic expression containing
parentheses.

Fixed a bug in handling of files that do not terminate in a newline.

0.93 released January 1997
--------------------------

This release went out in a great hurry after semi-crippling bugs
were found in 0.92.

Really _did_ fix the stack overflows this time. *blush*

Had problems with EA instruction sizes changing between passes, when
an offset contained a forward reference and so 4 bytes were
allocated for the offset in pass one; by pass two the symbol had
been defined and happened to be a small absolute value, so only 1
byte got allocated, causing instruction size mismatch between passes
and hence incorrect address calculations. Fixed.

Stupid bug in the revised ELF section generation fixed (associated
string-table section for .symtab was hard-coded as 7, even when this
didn't fit with the real section table). Was causing `ld' to
seg-fault under Linux.

Included a new Borland C makefile, Makefile.bc2, donated by Fox
Cutter <lmb@comtch.iea.com>.

0.94 released April 1997
------------------------

Major item: added the macro processor.

Added undocumented instructions SMI, IBTS, XBTS and LOADALL286. Also
reorganised CMPXCHG instruction into early-486 and Pentium forms.
Thanks to Thobias Jones for the information.

Fixed two more stupid bugs in ELF, which were causing `ld' to
continue to seg-fault in a lot of non-trivial cases.

Fixed a seg-fault in the label manager.

Stopped FBLD and FBSTP from _requiring_ the TWORD keyword, which is
the only option for BCD loads/stores in any case.

Ensured FLDCW, FSTCW and FSTSW can cope with the WORD keyword, if
anyone bothers to provide it. Previously they complained unless no
keyword at all was present.

Some forms of FDIV/FDIVR and FSUB/FSUBR were still inverted: a
vestige of a bug that I thought had been fixed in 0.92. This was
fixed, hopefully for good this time...

Another minor phase error (insofar as a phase error can _ever_ be
minor) fixed, this one occurring in code of the form
   rol ax,forward_reference
   forward_reference equ 1

The number supplied to TIMES is now sanity-checked for positivity,
and also may be greater than 64K (which previously didn't work on
16-bit systems).

Added Watcom C makefiles, and misc/pmw.bat, donated by Dominik Behr.

Added the INCBIN pseudo-opcode.

Due to the advent of the preprocessor, the [INCLUDE] and [INC]
directives have become obsolete. They are still supported in this
version, with a warning, but won't be in the next.

Fixed a bug in OBJ format, which caused incorrect object records to
be output when absolute labels were made global.

Updates to RDOFF subdirectory, and changes to outrdf.c.

0.95 released July 1997
-----------------------

Fixed yet another ELF bug. This one manifested if the user relied on
the default segment, and attempted to define global symbols without
first explicitly declaring the target segment.

Added makefiles (for NASM and the RDF tools) to build Win32 console
apps under Symantec C++. Donated by Mark Junker.

Added `macros.bas' and `insns.bas', QBasic versions of the Perl
scripts that convert `standard.mac' to `macros.c' and convert
`insns.dat' to `insnsa.c' and `insnsd.c'. Also thanks to Mark
Junker.

Changed the diassembled forms of the conditional instructions so
that JB is now emitted as JC, and other similar changes. Suggested
list by Ulrich Doewich.

Added `@' to the list of valid characters to begin an identifier
with.

Documentary changes, notably the addition of the `Common Problems'
section in nasm.doc.

Fixed a bug relating to 32-bit PC-relative fixups in OBJ.

Fixed a bug in perm_copy() in labels.c which was causing exceptions
in cleanup_labels() on some systems.

Positivity sanity check in TIMES argument changed from a warning to
an error following a further complaint.

Changed the acceptable limits on byte and word operands to allow
things like `~10111001b' to work.

Fixed a major problem in the preprocessor which caused seg-faults if
macro definitions contained blank lines or comment-only lines.

Fixed inadequate error checking on the commas separating the
arguments to `db', `dw' etc.

Fixed a crippling bug in the handling of macros with operand counts
defined with a `+' modifier.

Fixed a bug whereby object file formats which stored the input file
name in the output file (such as OBJ and COFF) weren't doing so
correctly when the output file name was specified on the command
line.

Removed [INC] and [INCLUDE] support for good, since they were
obsolete anyway.

Fixed a bug in OBJ which caused all fixups to be output in 16-bit
(old-format) FIXUPP records, rather than putting the 32-bit ones in
FIXUPP32 (new-format) records.

Added, tentatively, OS/2 object file support (as a minor variant on
OBJ).

Updates to Fox Cutter's Borland C makefile, Makefile.bc2.

Removed a spurious second fclose() on the output file.

Added the `-s' command line option to redirect all messages which
would go to stderr (errors, help text) to stdout instead.

Added the `-w' command line option to selectively suppress some
classes of assembly warning messages.

Added the `-p' pre-include and `-d' pre-define command-line options.

Added an include file search path: the `-i' command line option.

Fixed a silly little preprocessor bug whereby starting a line with a
`%!' environment-variable reference caused an `unknown directive'
error.

Added the long-awaited listing file support: the `-l' command line
option.

Fixed a problem with OBJ format whereby, in the absence of any
explicit segment definition, non-global symbols declared in the
implicit default segment generated spurious EXTDEF records in the
output.

Added the NASM environment variable.

From this version forward, Win32 console-mode binaries will be
included in the DOS distribution in addition to the 16-bit binaries.
Added Makefile.vc for this purpose.

Added `return 0;' to test/objlink.c to prevent compiler warnings.

Added the __NASM_MAJOR__ and __NASM_MINOR__ standard defines.

Added an alternative memory-reference syntax in which prefixing an
operand with `&' is equivalent to enclosing it in square brackets,
at the request of Fox Cutter.

Errors in pass two now cause the program to return a non-zero error
code, which they didn't before.

Fixed the single-line macro cycle detection, which didn't work at
all on macros with no parameters (caused an infinite loop). Also
changed the behaviour of single-line macro cycle detection to work
like cpp, so that macros like `extrn' as given in the documentation
can be implemented.

Fixed the implementation of WRT, which was too restrictive in that
you couldn't do `mov ax,[di+abc wrt dgroup]' because (di+abc) wasn't
a relocatable reference.

0.96 released November 1997
---------------------------

Fixed a bug whereby, if `nasm sourcefile' would cause a filename
collision warning and put output into `nasm.out', then `nasm
sourcefile -o outputfile' still gave the warning even though the
`-o' was honoured.

Fixed name pollution under Digital UNIX: one of its header files
defined R_SP, which broke the enum in nasm.h.

Fixed minor instruction table problems: FUCOM and FUCOMP didn't have
two-operand forms; NDISASM didn't recognise the longer register
forms of PUSH and POP (eg FF F3 for PUSH BX); TEST mem,imm32 was
flagged as undocumented; the 32-bit forms of CMOV had 16-bit operand
size prefixes; `AAD imm' and `AAM imm' are no longer flagged as
undocumented because the Intel Architecture reference documents
them.

Fixed a problem with the local-label mechanism, whereby strange
types of symbol (EQUs, auto-defined OBJ segment base symbols)
interfered with the `previous global label' value and screwed up
local labels.

Fixed a bug whereby the stub preprocessor didn't communicate with
the listing file generator, so that the -a and -l options in
conjunction would produce a useless listing file.

Merged `os2' object file format back into `obj', after discovering
that `obj' _also_ shouldn't have a link pass separator in a module
containing a non-trivial MODEND. Flat segments are now declared
using the FLAT attribute. `os2' is no longer a valid object format
name: use `obj'.

Removed the fixed-size temporary storage in the evaluator. Very very
long expressions (like `mov ax,1+1+1+1+...' for two hundred 1s or
so) should now no longer crash NASM.

Fixed a bug involving segfaults on disassembly of MMX instructions,
by changing the meaning of one of the operand-type flags in nasm.h.
This may cause other apparently unrelated MMX problems; it needs to
be tested thoroughly.

Fixed some buffer overrun problems with large OBJ output files.
Thanks to DJ Delorie for the bug report and fix.

Made preprocess-only mode actually listen to the %line markers as it
prints them, so that it can report errors more sanely.

Re-designed the evaluator to keep more sensible track of expressions
involving forward references: can now cope with previously-nightmare
situations such as
   mov ax,foo | bar
   foo equ 1
   bar equ 2

Added the ALIGN and ALIGNB standard macros.

Added PIC support in ELF: use of WRT to obtain the four extra
relocation types needed.

Added the ability for output file formats to define their own
extensions to the GLOBAL, COMMON and EXTERN directives.

Implemented common-variable alignment, and global-symbol type and
size declarations, in ELF.

Implemented NEAR and FAR keywords for common variables, plus
far-common element size specification, in OBJ.

Added a feature whereby EXTERNs and COMMONs in OBJ can be given a
default WRT specification (either a segment or a group).

Transformed the Unix NASM archive into an auto-configuring package.

Added a sanity-check for people applying SEG to things which are
already segment bases: this previously went unnoticed by the SEG
processing and caused OBJ-driver panics later.

Added the ability, in OBJ format, to deal with `MOV EAX,<segment>'
type references: OBJ doesn't directly support dword-size segment
base fixups, but as long as the low two bytes of the constant term
are zero, a word-size fixup can be generated instead and it will
work.

Added the ability to specify sections' alignment requirements in
Win32 object files and pure binary files.

Added preprocess-time expression evaluation: the %assign (and
%iassign) directive and the bare %if (and %elif) conditional. Added
relational operators to the evaluator, for use only in %if
constructs: the standard relationals = < > <= >= <> (and C-like
synonyms == and !=) plus low-precedence logical operators &&, ^^ and
||.

Added a preprocessor repeat construct: %rep / %exitrep / %endrep.

Added the __FILE__ and __LINE__ standard macros.

Added a sanity check for number constants being greater than
0xFFFFFFFF. The warning can be disabled.

Added the %0 token whereby a variadic multi-line macro can tell how
many parameters it's been given in a specific invocation.

Added %rotate, allowing multi-line macro parameters to be cycled.

Added the `*' option for the maximum parameter count on multi-line
macros, allowing them to take arbitrarily many parameters.

Added the ability for the user-level forms of EXTERN, GLOBAL and
COMMON to take more than one argument.

Added the IMPORT and EXPORT directives in OBJ format, to deal with
Windows DLLs.

Added some more preprocessor %if constructs: %ifidn / %ifidni (exact
textual identity), and %ifid / %ifnum / %ifstr (token type testing).

Added the ability to distinguish SHL AX,1 (the 8086 version) from
SHL AX,BYTE 1 (the 286-and-upwards version whose constant happens to
be 1).

Added NetBSD/FreeBSD/OpenBSD's variant of a.out format, complete
with PIC shared library features.

Changed NASM's idiosyncratic handling of FCLEX, FDISI, FENI, FINIT,
FSAVE, FSTCW, FSTENV, and FSTSW to bring it into line with the
otherwise accepted standard. The previous behaviour, though it was a
deliberate feature, was a deliberate feature based on a
misunderstanding. Apologies for the inconvenience.

Improved the flexibility of ABSOLUTE: you can now give it an
expression rather than being restricted to a constant, and it can
take relocatable arguments as well.

Added the ability for a variable to be declared as EXTERN multiple
times, and the subsequent definitions are just ignored.

We now allow instruction prefixes (CS, DS, LOCK, REPZ etc) to be
alone on a line (without a following instruction).

Improved sanity checks on whether the arguments to EXTERN, GLOBAL
and COMMON are valid identifiers.

Added misc/exebin.mac to allow direct generation of .EXE files by
hacking up an EXE header using DB and DW; also added test/binexe.asm
to demonstrate the use of this. Thanks to Yann Guidon for
contributing the EXE header code.

ndisasm forgot to check whether the input file had been successfully
opened. Now it does. Doh!

Added the Cyrix extensions to the MMX instruction set.

Added a hinting mechanism to allow [EAX+EBX] and [EBX+EAX] to be
assembled differently. This is important since [ESI+EBP] and
[EBP+ESI] have different default base segment registers.

Added support for the PharLap OMF extension for 4096-byte segment
alignment.

0.97 released December 1997
---------------------------

This was entirely a bug-fix release to 0.96, which seems to have got
cursed. Silly me.

Fixed stupid mistake in OBJ which caused `MOV EAX,<constant>' to
fail. Caused by an error in the `MOV EAX,<segment>' support.

ndisasm hung at EOF when compiled with lcc on Linux because lcc on
Linux somehow breaks feof(). ndisasm now does not rely on feof().

A heading in the documentation was missing due to a markup error in
the indexing. Fixed.

Fixed failure to update all pointers on realloc() within extended-
operand code in parser.c. Was causing wrong behaviour and seg faults
on lines such as `dd 0.0,0.0,0.0,0.0,...'

Fixed a subtle preprocessor bug whereby invoking one multi-line
macro on the first line of the expansion of another, when the second
had been invoked with a label defined before it, didn't expand the
inner macro. 

Added internal.doc back in to the distribution archives - it was
missing in 0.96 *blush*

Fixed bug causing 0.96 to be unable to assemble its own test files,
specifically objtest.asm. *blush again*

Fixed seg-faults and bogus error messages caused by mismatching
%rep and %endrep within multi-line macro definitions.

Fixed a problem with buffer overrun in OBJ, which was causing
corruption at ends of long PUBDEF records.

Separated DOS archives into main-program and documentation to reduce
download size.

0.98 released May 1999
----------------------

Fixed a bug whereby STRUC didn't work at all in RDF.

Fixed a problem with group specification in PUBDEFs in OBJ.

Improved ease of adding new output formats. Contribution due to
Fox Cutter.

Fixed a bug in relocations in the `bin' format: was showing up when
a relocatable reference crossed an 8192-byte boundary in any output
section.

Fixed a bug in local labels: local-label lookups were inconsistent
between passes one and two if an EQU occurred between the definition
of a global label and the subsequent use of a local label local to
that global.

Fixed a seg-fault in the preprocessor (again) which happened when
you use a blank line as the first line of a multi-line macro
definition and then defined a label on the same line as a call to
that macro.

Fixed a stale-pointer bug in the handling of the NASM environment
variable. Thanks to Thomas McWilliams.

ELF had a hard limit on the number of sections which caused
segfaults when transgressed. Fixed.

Added ability for ndisasm to read from stdin by using `-' as the
filename.

ndisasm wasn't outputting the TO keyword. Fixed.

Fixed error cascade on bogus expression in %if - an error in
evaluation was causing the entire %if to be discarded, thus creating
trouble later when the %else or %endif was encountered.

Forward reference tracking was instruction-granular not operand-
granular, which was causing 286-specific code to be generated
needlessly on code of the form `shr word [forwardref],1'. Thanks to
Jim Hague for sending a patch.

All messages now appear on stdout, as sending them to stderr serves
no useful purpose other than to make redirection difficult.

Fixed the problem with EQUs pointing to an external symbol - this
now generates an error message.

Allowed multiple size prefixes to an operand, of which only the first
is taken into account.

Incorporated John Fine's changes, including fixes of a large number
of preprocessor bugs, some small problems in OBJ, and a reworking of
label handling to define labels before their line is assembled, rather
than after.

Reformatted a lot of the source code to be more readable. Included
'coding.txt' as a guideline for how to format code for contributors.

Stopped nested %reps causing a panic - they now cause a slightly more
friendly error message instead.

Fixed floating point constant problems (patch by Pedro Gimeno)

Fixed the return value of insn_size() not being checked for -1, indicating
an error.

Incorporated 3D now instructions.

Fixed the 'mov eax, eax + ebx' bug.

Fixed the GLOBAL EQU bug in ELF. Released developers release 3.

Incorporated John Fine's command line parsing changes

Incorporated David Lindauer's OMF debug support

Made changes for LCC 4.0 support (__NASM_CDecl__, removed register size
specification warning when sizes agree).

Released NASM 0.98 Pre-release 1

fixed bug in outcoff.c to do with truncating section names longer
than 8 characters, referencing beyond end of string; 0.98 pre-release 2

added response file support, improved command line handling, new layout
help screen

fixed limit checking bug, 'OUT byte nn, reg' bug, and a couple of rdoff
related bugs, updated Wishlist; 0.98 Prerelease 3.

See the file "MODIFIED" for changes after 0.98p3.