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                   ; Instead of INT1
  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 ;-----------------------------------------------------------------------------
 102 ; Bug added by John in preproc.c 0.98-J4, removed by John in 0.98-J5
 103 ;
 104 ; Tested here to make sure it stays removed
 105 ;
 106 %macro TestElse 1
 107 %if %1=0
 108 %elif %1=1
 109 nop
 110 %endif
 111 %endmacro
 112 TestElse 1
 113
 114 %ifdef oldmsg
 115 ;***************************************************************
 116 ;
 117 ; The following examples will generate error messages in 0.97 and will generate
 118 ; correct output in the new version.
 119
 120 ;-----------------------------------------------------------------------------
 121 ; Bug fixed by Simon in isns.dat
 122 ;
 123 ; The optional "near" was not permitted on JMP and CALL
 124 ;
 125         jmp near here
 126
 127 ;-----------------------------------------------------------------------------
 128 ; Feature added by Simon in stdscan()
 129 ;
 130 ; You can now use the numeric value of strings in %assign
 131 ;
 132 %assign xxx 'ABCD'
 133         dd xxx
 134
 135 ;-----------------------------------------------------------------------------
 136 ; Feature added by John in add_vectors()
 137 ;
 138 ; Stranger address expressions are now supported as long as they resolve to
 139 ; something valid.
 140 ;
 141         mov ax, [eax + ebx + ecx - eax]
 142
 143 ;-----------------------------------------------------------------------------
 144 ; Bug fixed by Simon in ???
 145 ;
 146 ; The EQU directive affected local labels in a way that was inconsistent
 147 ; between passes
 148 ;
 149 .local:
 150 neither equ $
 151         jmp .local
 152
 153 ;-----------------------------------------------------------------------------
 154 ; Feature added by Jules in parse_line
 155 ;
 156 ; You can override a size specifier
 157 ;
 158 %define arg1 dword [bp+4]
 159         cmp word arg1, 2
 160
 161 ;-----------------------------------------------------------------------------
 162 ; Bug fixed by John in preproc.c
 163 ;
 164 ; You could not use a label on the same line with a macro invocation, if the
 165 ; macro definition began with a preprocessor directive.
 166 ;
 167         struc mytype
 168 .long   resd    1
 169         endstruc
 170
 171 lbl     istruc mytype
 172         at mytype.long, dd 'ABCD'
 173         iend
 174
 175 ;-----------------------------------------------------------------------------
 176 ; Warning removed by John in preproc.c
 177 ;
 178 ; In order to allow macros that extend the definition of instructions, I
 179 ; disabled the warning on a multi-line macro referencing itself.
 180 ;
 181 %endif                  ;NASM 0.97 doesn't handle %0 etc. inside false %if
 182 %macro push 1-*         ;
 183 %rep %0                 ;
 184 push %1                 ;
 185 %rotate 1               ;
 186 %endrep                 ;
 187 %endmacro               ;
 188 %ifdef oldmsg           ;
 189
 190         push ax,bx
 191
 192 ;-----------------------------------------------------------------------------
 193 ; Warning removed by John in preproc.c
 194 ;
 195 ; To support other types of macros that extend the definition of instructions,
 196 ; I disabled the warning on a multi-line macro called with the wrong number of
 197 ; parameters.  PUSH and POP can be extended equally well by either method, but
 198 ; other intruction extensions may need one method or the other, so I made both
 199 ; work.
 200 ;
 201 ; Note that neither of these warnings was really needed, because a later stage
 202 ; of NASM would almost always give an adequate error message if the macro use
 203 ; really was wrong.
 204 ;
 205 %endif
 206 %macro pop 2-*
 207 %rep %0
 208 pop %1
 209 %rotate 1
 210 %endrep
 211 %endmacro
 212 %ifdef oldmsg
 213
 214         pop ax,bx
 215 %endif
 216
 217
 218 %ifdef newmsg  ;***************************************************************
 219
 220 ;-----------------------------------------------------------------------------
 221 ; Bug fixed by John in parse_line()  (and other routines)
 222 ;
 223 ; This invalid code used to assemble without errors
 224 ;
 225 myself equ myself+1
 226         jmp myself
 227
 228 ;-----------------------------------------------------------------------------
 229 ; Change made by John in preproc.c
 230 ;
 231 ; In 0.97, an id that appears as a label on a macro invocation was always
 232 ; prepended to the first line of the macro expansion.  That caused several
 233 ; bugs, but also could be used in tricks like the arg macro in c16.mac and
 234 ; c32.mac.
 235 ;
 236 ; In version X, an id that appears as a label on a macro invocation will
 237 ; normally be defined as a label for the address at which the macro is
 238 ; invoked, regardless of whether the first line of the macro expansion is
 239 ; something that can take a label.  The new token %00 may be used for any
 240 ; of the situations in which the old prepend behavior was doing something
 241 ; tricky but useful.  %00 can also be used more than once and in places
 242 ; other than the start of the expansion.
 243 ;
 244 %endif
 245 %assign arg_off 0
 246
 247 %imacro arg 0-1 2               ;arg defined the old way
 248           equ arg_off
 249 %assign arg_off %1+arg_off
 250 %endmacro
 251
 252 %ifdef newmsg
 253 arg_example arg
 254 %endif
 255
 256 %imacro arg2 0-1 2              ;arg defined the new way
 257 %00       equ arg_off
 258 %assign arg_off %1+arg_off
 259 %endmacro
 260
 261 %ifdef oldmsg
 262 arg_example2 arg2
 263
 264 ;-----------------------------------------------------------------------------
 265 ; Change made by Jules and John in INSNS.DAT
 266 ;
 267 ; Various instruction in which the size of an immediate is built-in to the
 268 ; instruction set, now allow you to redundantly specify that size as long
 269 ; as you specify it correctly
 270 ;
 271         AAD     byte 5
 272         AAM     byte 5
 273         BT      bx, byte 3
 274         BTC     cx, byte 4
 275         BTR     dx, byte 5
 276         BTS     si, byte 6
 277         IN      eax, byte 0x40
 278         INT     byte 21h
 279         OUT     byte 70h, ax
 280         RET     word 2
 281         RETN    word 2
 282         RETF    word 4
 283
 284 ; note "ENTER" has not been changed yet.
 285
 286 ;-----------------------------------------------------------------------------
 287 ; Enhancement by hpa in insns.dat et al
 288 ;
 289 ; Simplified adding new instructions, and added some missing instructions
 290 ;
 291         int03                   ; Instead of INT3
 292         ud1                     ; No documented mnemonic for this one
 293         ud2
 294         sysenter
 295         sysexit
 296         syscall
 297         sysret
 298         fxsave [ebx]
 299         fxrstor [es:ebx+esi*4+0x3000]
 300
 301 ;-----------------------------------------------------------------------------
 302 ; Enhancement by hpa in insns.dat et al
 303 ;
 304 ; Actually make SSE work, and use the -p option to ndisasm to select
 305 ; one of several aliased opcodes
 306 ;
 307         sqrtps xmm0,[ebx+10]    ; SSE opcode
 308         paddsiw mm0,[ebx+10]    ; Cyrix opcode with the same byte seq.
 309
 310 %endif
 311
 312 %ifdef oldcrash  ;*************************************************************
 313
 314 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___
 315
 316 ;-----------------------------------------------------------------------------
 317 ; Bug fixed by John in preproc.c
 318 ;
 319 ; Builds of NASM that prohibit dereferencing a NULL pointer used to crash if a
 320 ; macro that started with a blank line was invoked with a label
 321 ;
 322 %macro empty_macro 0
 323
 324 %endm
 325
 326 emlabel empty_macro
 327         jmp     emlabel
 328
 329 ;-----------------------------------------------------------------------------
 330 ; Enhancement by Conan Brink in preproc.c
 331 ;
 332 ; Allow %rep to be nested
 333 ;
 334 %rep 4
 335 %rep 5
 336         nop
 337 %endrep
 338 %endrep
 339
 340 %endif