changes.asm

   1 ;This file demonstrates many of the differences between NASM version X and NASM
   2 ;version 0.97
   3 ;
   4 ; changes.asm is copyright (C) 1998 John S. Fine
   5 ;
   6 ;  It may be redistributed under the same conditions as NASM as described in
   7 ;  Licence file in the NASM archive
   8 ;_________________________________
   9 ;
  10 ;  nasm changes.asm -l changes.lst
  11 ;
  12 ; When assembled without any -d switches, it includes examples which:
  13 ;       Work correctly in version X
  14 ;  and  Work incorrectly and/or display warnings in version 0.97
  15 ;  and  Do not prevent the generation of output in version 0.97
  16 ;
  17 ; Not all the differences can be seen in the .lst file.  I suggest that you use
  18 ; "ndisasm changes"  to examine the code actually generated.
  19 ;_________________________________
  20 ;
  21 ;  nasm changes.asm -l changes.lst -doldmsg
  22 ;
  23 ; When assembled with -doldmsg, it adds examples which:
  24 ;       Work correctly in version X
  25 ;  and  Generate error messages in version 0.97 and do not generate output
  26 ;_________________________________
  27 ;
  28 ;  nasm changes.asm -l changes.lst -doldcrash
  29 ;
  30 ; When assembled with -doldcrash, it adds examples which:
  31 ;       Work correctly in version X
  32 ;  and  Cause NASM to crash in version 0.97
  33 ;_________________________________
  34 ;
  35 ;  nasm changes.asm -l changes.lst -dnewmsg
  36 ;
  37 ; When assembled with -dnewmsg, it adds examples which:
  38 ;       Generate error messages in version X
  39 ;  and  Generate wrong output without warning or error message in version 0.97
  40 ;-----------------------------------------------------------------------------
  41
  42 ; Please note that I have reported the name of the person who made the
  43 ; correction based on very limited information.  In several cases, I am sure I
  44 ; will identify the wrong author.  Please send me any corrections;  I don't
  45 ; intend to insult or exclude anyone.
  46
  47 ;-----------------------------------------------------------------------------
  48 ; Bug fixed by Simon in assemble()
  49 ;
  50 ; The following generated "call next" / "call next-1" instead of
  51 ; two copies of "call next"
  52 ;
  53         times 2 a16 call next
  54 next:
  55
  56 ;-----------------------------------------------------------------------------
  57 ; Bug fixed by John in parse_line()  (and other routines)
  58 ;
  59 ; This used to jmp to prior.1, when it should be here.1
  60 ;
  61 prior:
  62 .1:
  63 here:   jmp     .1
  64 .1:
  65
  66 ;-----------------------------------------------------------------------------
  67 ; Bug fixed by John in assemble()
  68 ;
  69 ; Strings used in dq and dt were not zero filled correctly
  70 ;
  71         dq      'b'
  72
  73
  74 ;-----------------------------------------------------------------------------
  75 ; Bug fixed by Simon in isn_names[]
  76 ;
  77 ; Was not recognised as an instruction
  78 ;
  79         int01
  80
  81 ;-----------------------------------------------------------------------------
  82 ; Bug fixed by Jim Hague in ???
  83 ;
  84 ; Forward references were instruction level rather than per operand
  85 ;
  86         shr word [forwardref],1
  87 forwardref:
  88
  89 ;-----------------------------------------------------------------------------
  90 ; Bug fixed by John in preproc.c
  91 ;
  92 ; It used to silently discard id characters appended to a multi-line
  93 ; macro parameter (such as the x in %1x below).
  94 ;
  95 %macro xxx 1
  96 %1: nop
  97 %{1}x: jmp %1x
  98 %endmacro
  99 xxx yyy
 100
 101 %ifdef oldmsg
 102 ;***************************************************************
 103 ;
 104 ; The following examples will generate error messages in 0.97 and will generate
 105 ; correct output in the new version.
 106
 107 ;-----------------------------------------------------------------------------
 108 ; Bug fixed by Simon in isns.dat
 109 ;
 110 ; The optional "near" was not permitted on JMP and CALL
 111 ;
 112         jmp near here
 113
 114 ;-----------------------------------------------------------------------------
 115 ; Feature added by Simon in stdscan()
 116 ;
 117 ; You can now use the numeric value of strings in %assign
 118 ;
 119 %assign xxx 'ABCD'
 120         dd xxx
 121
 122 ;-----------------------------------------------------------------------------
 123 ; Feature added by John in add_vectors()
 124 ;
 125 ; Stranger address expressions are now supported as long as they resolve to
 126 ; something valid.
 127 ;
 128         mov ax, [eax + ebx + ecx - eax]
 129
 130 ;-----------------------------------------------------------------------------
 131 ; Bug fixed by Simon in ???
 132 ;
 133 ; The EQU directive affected local labels in a way that was inconsistent
 134 ; between passes
 135 ;
 136 .local:
 137 neither equ $
 138         jmp .local
 139
 140 ;-----------------------------------------------------------------------------
 141 ; Feature added by Jules in parse_line
 142 ;
 143 ; You can override a size specifier
 144 ;
 145 %define arg1 dword [bp+4]
 146         cmp word arg1, 2
 147
 148 ;-----------------------------------------------------------------------------
 149 ; Bug fixed by John in preproc.c
 150 ;
 151 ; You could not use a label on the same line with a macro invocation, if the
 152 ; macro definition began with a preprocessor directive.
 153 ;
 154         struc mytype
 155 .long   resd    1
 156         endstruc
 157
 158 lbl     istruc mytype
 159         at mytype.long, dd 'ABCD'
 160         iend
 161
 162 ;-----------------------------------------------------------------------------
 163 ; Warning removed by John in preproc.c
 164 ;
 165 ; In order to allow macros that extend the definition of instructions, I
 166 ; disabled the warning on a multi-line macro referencing itself.
 167 ;
 168 %endif                  ;NASM 0.97 doesn't handle %0 etc. inside false %if
 169 %macro push 1-*         ;
 170 %rep %0                 ;
 171 push %1                 ;
 172 %rotate 1               ;
 173 %endrep                 ;
 174 %endmacro               ;
 175 %ifdef oldmsg           ;
 176
 177         push ax,bx
 178
 179 ;-----------------------------------------------------------------------------
 180 ; Warning removed by John in preproc.c
 181 ;
 182 ; To support other types of macros that extend the definition of instructions,
 183 ; I disabled the warning on a multi-line macro called with the wrong number of
 184 ; parameters.  PUSH and POP can be extended equally well by either method, but
 185 ; other intruction extensions may need one method or the other, so I made both
 186 ; work.
 187 ;
 188 ; Note that neither of these warnings was really needed, because a later stage
 189 ; of NASM would almost always give an adequate error message if the macro use
 190 ; really was wrong.
 191 ;
 192 %endif
 193 %macro pop 2-*
 194 %rep %0
 195 pop %1
 196 %rotate 1
 197 %endrep
 198 %endmacro
 199 %ifdef oldmsg
 200
 201         pop ax,bx
 202 %endif
 203
 204
 205 %ifdef newmsg  ;***************************************************************
 206
 207 ;-----------------------------------------------------------------------------
 208 ; Bug fixed by John in parse_line()  (and other routines)
 209 ;
 210 ; This invalid code used to assemble without errors
 211 ;
 212 myself equ myself+1
 213         jmp myself
 214
 215 ;-----------------------------------------------------------------------------
 216 ; Change made by John in preproc.c
 217 ;
 218 ; In 0.97, an id that appears as a label on a macro invocation was always
 219 ; prepended to the first line of the macro expansion.  That caused several
 220 ; bugs, but also could be used in tricks like the arg macro in c16.mac and
 221 ; c32.mac.
 222 ;
 223 ; In version X, an id that appears as a label on a macro invocation will
 224 ; normally be defined as a label for the address at which the macro is
 225 ; invoked, regardless of whether the first line of the macro expansion is
 226 ; something that can take a label.  The new token %00 may be used for any
 227 ; of the situations in which the old prepend behavior was doing something
 228 ; tricky but useful.  %00 can also be used more than once and in places
 229 ; other than the start of the expansion.
 230 ;
 231 %endif
 232 %assign arg_off 0
 233
 234 %imacro arg 0-1 2               ;arg defined the old way
 235           equ arg_off
 236 %assign arg_off %1+arg_off
 237 %endmacro
 238
 239 %ifdef newmsg
 240 arg_example arg
 241 %endif
 242
 243 %imacro arg2 0-1 2              ;arg defined the new way
 244 %00       equ arg_off
 245 %assign arg_off %1+arg_off
 246 %endmacro
 247
 248 %ifdef oldmsg
 249 arg_example2 arg2
 250
 251 ;-----------------------------------------------------------------------------
 252 ; Change made by Jules and John in INSNS.DAT
 253 ;
 254 ; Various instruction in which the size of an immediate is built-in to the
 255 ; instruction set, now allow you to redundantly specify that size as long
 256 ; as you specify it correctly
 257 ;
 258         AAD     byte 5
 259         AAM     byte 5
 260         BT      bx, byte 3
 261         BTC     cx, byte 4
 262         BTR     dx, byte 5
 263         BTS     si, byte 6
 264         IN      eax, byte 0x40
 265         INT     byte 21h
 266         OUT     byte 70h, ax
 267         RET     word 2
 268         RETN    word 2
 269         RETF    word 4
 270
 271 ; note "ENTER" has not been changed yet.
 272
 273 %endif
 274
 275 %ifdef oldcrash  ;*************************************************************
 276
 277 This_label_is_256_characters_long__There_used_to_be_a_bug_in_stdscan_which_made_it_crash_when_it_did_a_keyword_search_on_any_label_longer_than_255_characters__Now_anything_longer_than_MAX_KEYWORD_is_always_a_symbol__It_will_not_even_try_a_keyword_search___
 278
 279 ;-----------------------------------------------------------------------------
 280 ; Bug fixed by John in preproc.c
 281 ;
 282 ; Builds of NASM that prohibit dereferencing a NULL pointer used to crash if a
 283 ; macro that started with a blank line was invoked with a label
 284 ;
 285 %macro empty_macro 0
 286
 287 %endm
 288
 289 emlabel empty_macro
 290         jmp     emlabel
 291
 292 %endif