ASM ALIGN statement

Purpose | Identify an assembly-language statement. PowerBASIC's Inline Assembler supports 8086/8088, 80286, 80386, 80486, Pentium, Floating-Point, SIMD and MMX instructions.
Syntax | {! | ASM} {opcode | label} {! | ASM} ALIGN boundary

Remarks

This statement allows you to place assembly-language code within your PowerBASIC source code. An exclamation mark (!) serves as a shortcut for the ASM keyword.

Each group of ASM statements must preserve the following CPU registers if the assembler code causes them to change: EBX, ESI, EDI, ESP, EBP, and all segment registers. See Saving Registers for more information.

No other statements may appear on the same line as an ASM statement; however, comments are acceptable.

! DB 1, 2, 3, 4, 5

! DD &H45001222, &HFFFF4327

Any variable referenced in an assembly-language statement must be defined prior to use. For example:

x% = 10

! MOV AX, x%

You cannot access the target of a pointer with a single ASM statement as you might do in BASIC source code. Instead, you must use the pointer address indirectly. To simulate the BASIC statement INCR @x, you would write:

DIM x AS INTEGER PTR

ASM MOV EAX, x ; EAX holds a pointer to an Integer

ASM INC WORD PTR [EAX] ; Add one to target value

String literals of up to four characters may be used in Inline Assembler code:

! MOV AL, "a" ; move char a into reg AL

! MOV AX, "ab" ; move chars ab into reg AX

! ; "a" into AL, "b" into AH

! MOV EAX, "abcd" ; move chars abcd into reg EAX

PowerBASIC recognizes either an apostrophe ( ' ) or a semi-colon ( ; ) to specify a comment after a line of assembler code:

! PUSH EAX ; save the EAX register

! PUSH EBX ' save the EBX register

ALIGN

ASM ALIGN is used in critical situations to gain maximum efficiency from assembler code sections.

ASM ALIGN is used to round up the instruction location to a power of two address. The boundary parameter shown must be a power of two, in the range of 2 through 256.

PowerBASIC inserts NOP instructions into the code section to bring the instruction location up to the desired address. If the instruction location is already at a multiple of boundary, ALIGN has no effect.

The #ALIGN metastatement functions in the same respect as ASM ALIGN, but the ASM ALIGN statement is more suited to being used in a PREFIX/END PREFIX block.

Restrictions | Care should be exercised to ensure registers are appropriately preserved when Inline Assembler code is intermixed with BASIC statements. See Saving Registers for more information.
See also | The Inline Assembler, ASMDATA

Example

To add the values a&, b&, and c&, you would write:

LOCAL a&, b&, c&, z&

! MOV EAX, a&

! ADD EAX, b&

! ADD EAX, c&

! MOV z&, EAX

Notes

The follow lists outline the supported mnemonics, data types, operators, and registers that can be used with the ASM statement.

The ASM statement supports the following mnemonics:

AAA, AAD, AAM, AAS, ADC, ADD, ADDPD, ADDPS, ADDSD, ADDSS, ADDSUBPD, ADDSUBPS, ANDNPD, ANDNPS, ANDPD, ANDPS, AND

BLENDPD, BLENDPS, BLENDVPD, BLENDVPS, BOUND, BSF, BSR, BSWAP, BT, BTC, BTR, BTS

CALL, CBW, CWD, CDQ, CLC, CLD, CLFLUSH, CLI, CMC, CMOVA, CMOVAE, CMOVB, CMOVBE, CMOVC, CMOVE, CMOVG, CMOVGE, CMOVL, CMOVLE, CMOVNA, CMOVNAE, CMOVNB, CMOVNBE, CMOVNC, CMOVNE, CMOVNG, CMOVNGE, CMOVNL, CMOVNLE, CMOVNO, CMOVNP, CMOVNS, CMOVNZ, CMOVO, CMOVP, CMOVPE, CMOVPO, CMOVS, CMOVZ, CMP, CMPPD, CMPPS, CMPSB, CMPSD, CMPSS, CMPSW, CMPXCHG, CMPXCHG8B, COMISD, COMISS, CPUID, CRC32, CVTDQ2PD, CVTDQ2PS, CVTPD2DQ, CVTPD2PI, CVTPD2PS, CVTPI2PD, CVTPI2PS, CVTPS2DQ, CVTPS2PD, CVTPS2PI, CVTSD2SI, CVTSD2SS, CVTSI2SD, CVTSI2SS, CVTSS2SD, CVTSS2SI, CVTTPD2DQ, CVTTPD2PI, CVTTPS2DQ, CVTTPS2PI, CVTTSD2SI, CVTTSS2SI, CWDE

DAA, DAS, DEC, DIV, DIVPD, DIVPS, DIVSD, DIVSS, DPPD, DPPS

EMMS, ENTER, EXTRACTPS

F2XM1, FABS, FADD, FADDP, FBLD, FBSTP, FCHS, FCLEX, FCMOVB, FCMOVBE, FCMOVE, FCMOVNB, FCMOVNBE, FCMOVNE, FCMOVNU, FCMOVU, FCOM, FCOMI, FCOMIP, FCOMP, FCOMPP, FCOS, FDECSTP, FDIV, FDIVP, FDIVR, FDIVRP, FFREE, FIADD, FICOM, FICOMP, FIDIV, FIDIVR, FILD, FIMUL, FINCSTP, FINIT, FIST, FISTP, FISTTP, FISUB, FISUBR, FLD, FLD1, FLDCW, FLDENV, FLDL2E, FLDL2T, FLDLG2, FLDLN2, FLDPI, FLDZ, FMUL, FMULP, FNCLEX, FNINIT, FNLDCW, FNOP, FNSAVE, FNSTCW, FNSTENV, FNSTSW, FPATAN, FPREM, FPREM1, FPTAN, FRNDINT, FRSTOR, FSAVE, FSCALE, FSIN, FSINCOS, FSQRT, FST, FSTCW, FSTENV, FSTP, FSTSW, FSUB, FSUBP, FSUBR, FSUBRP, FTST, FUCOM, FUCOMI, FUCOMIP, FUCOMP, FUCOMPP, FWAIT, FXAM, FXCH, FXRSTOR, FXSAVE, FXTRACT, FYL2X, FYL2XP1

HADDPD, HADDPS, HLT, HSUBPD, HSUBPS

IDIV, IMUL, IN, INC, INSB, INSD, INSERTPS, INSW, INT, INTO, IRET, IRETD

JA, JAE, JB, JBE, JC, JE, JECXZ, JG, JGE, JL, JLE, JMP, JNA, JNAE, JNB, JNBE, JNC, JNE, JNG, JNGE, JNL, JNLE, JNO, JNP, JNS, JNZ, JO, JP, JPE, JPO, JS, JZ

LAHF, LAR, LDDQU, LDMXCSR, LDS, LEA, LEAVE, LES, LFENCE, LFS, LGS, LOCK, LODSB, LODSD, LODSW, LOOP, LOOPE, LOOPNE, LOOPNZ, LOOPZ, LSL, LSS

MASKMOVDQU, MASKMOVQ, MAXPD, MAXPS, MAXSD, MAXSS, MFENCE, MINPD, MINPS, MINSD, MINSS, MONITOR, MOV, MOVAPD, MOVAPS, MOVD, MOVDDUP, MOVDQA, MOVDQU, MOVDQ2Q, MOVHLPS, MOVHPD, MOVHPS, MOVLHPS, MOVLPD, MOVLPS, MOVMSKPD, MOVMSKPS, MOVNTDQA, MOVNTDQ, MOVNTI, MOVNTPD, MOVNTPS, MOVNTQ, MOVQ2DQ, MOVQ, MOVSB, MOVSD, MOVSHDUP, MOVSLDUP, MOVSS, MOVSW, MOVSX, MOVUPD, MOVUPS, MOVZX, MPSADBW, MUL, MULPD, MULPS, MULSD, MULSS, MWAIT

NEG, NOP, NOT

OR, ORPD, ORPS, OUT, OUTSB, OUTSD, OUTSW

PABSB, PABSD, PABSW, PACKSSDW, PACKSSWB, PACKUSDW, PACKUSWB, PADDB, PADDD, PADDQ, PADDSB, PADDSW, PADDUSB, PADDUSW, PADDW, PALIGNR, PAND, PANDN, PAUSE, PAVGB, PAVGW, PBLENDVB, PBLENDW, PCMPEQB, PCMPEQD, PCMPEQW, PCMPEQQ, PCMPESTRI, PCMPESTRM, PCMPISTRI, PCMPISTRM, PCMPGTB, PCMPGTD, PCMPGTQ, PCMPGTW, PEXTRB, PEXTRD, PEXTRW, PHADDD, PHADDW, PHADDSW, PHMINPOSUW, PHSUBD, PHSUBSW, PHSUBW, PINSRB, PINSRD, PINSRW, PMADDUBSW, PMADDWD, PMAXSB, PMAXSD, PMAXSW, PMAXUB, PMAXUD, PMAXUW, PMINSB, PMINSD, PMINSW, PMINUB, PMINUD, PMINUW, PMOVMSKB, PMOVSXBW, PMOVSXBD, PMOVSXBQ, PMOVSXWD, PMOVSXWQ, PMOVSXDQ, PMOVZXBW, PMOVZXBD, PMOVZXBQ, PMOVZXWD, PMOVZXWQ, PMOVZXDQ, PMULDQ, PMULHRSW, PMULHUW, PMULHW, PMULLD, PMULLW, PMULUDQ, POP, POPA, POPAD, POPCNT, POPF, POPFD, POR, PREFETCHT0, PREFETCHT1, PREFETCHT2, PREFETCHNTA, PSADBW, PSHUFB, PSHUFD, PSHUFHW, PSHUFLW, PSHUFW, PSIGNB, PSIGND, PSIGNW, PSLLD, PSLLDQ, PSLLQ, PSLLW, PSRAD, PSRAW, PSRLD, PSRLDQ, PSRLD, PSRLQ, PSRLW, PSUBB, PSUBD, PSUBQ, PSUBW, PSUBSB, PSUBSW, PSUBUSB, PSUBUSW, PTEST, PUNPCKHBW, PUNPCKHDQ, PUNPCKHQDQ, PUNPCKHWD, PUNPCKLBW, PUNPCKLDQ, PUNPCKLQDQ, PUNPCKLWD, PUSH, PUSHA, PUSHAD, PUSHF, PUSHFD, PXOR

RCL, RCR, RCPPS, RCPSS, RDPMC, RDTSC, REP, REPE, REPNE, REPNZ, REPZ, RET, RETF, RETN, ROL, ROR, ROUNDPD, ROUNDPS, ROUNDSD, ROUNDSS, RSQRTPS, RSQRTSS

SAHF, SAL, SAR, SBB, SCASB, SCASD, SCASW, SETA, SETAE, SETB, SETBE, SETC, SETE, SETG, SETGE, SETL, SETLE, SETNA, SETNAE, SETNB, SETNBE, SETNC, SETNE, SETNG, SETNGE, SETNL, SETNLE, SETNO, SETNP, SETNS, SETNZ, SETO, SETP, SETPE, SETPO, SETS, SETZ, SFENCE, SHL, SHLD, SHR, SHRD, SHUFPD. SHUFPS, SQRTPD, SQRTPS, SQRTSD, SQRTSS, STC, STD, STI, STMXCSR, STOSB, STOSD, STOSW, SUB, SUBPD, SUBPS, SUBSD, SUBSS

TEST

UCOMISD, UCOMISS, UNPCKHPD, UNPCKHPS, UNPCKLPD, UNPCKLPS

VERR, VERW

WAIT

XADD, XCHG, XGETBV, XLAT, XOR, XORPD, XORPS, XRSTOR, XSAVE, XSETBV

The ASM statement supports the following data types and operators:

BYTE

DB, DD, DW, DWD, DWORD

FAR

NEAR

POINTER, PTR

QWD, QWORD

SHORT

TBY, TBYTE

WORD, WRD

The ASM statement supports the following registers:

Integer

32-bit | Low 16-bit | High 8-bit | Low 8-bit
EAX | AX | AH | AL
EBX | BX | BH | BL
ECX | CX | CH | CL
EDX | DX | DH | DL
ESI | SI |  |
EDI | DI |  |
ESP | SP |  |
EBP | BP |  |

Segments

CS, DS, ES, SS, FS, GS

MMX Registers

MM(0), MM(1), MM(2), MM(3), MM(4), MM(5), MM(6), MM(7)

MM0, MM1, MM2, MM3, MM4, MM5, MM6, MM7

Floating Point registers

ST(0), ST(1), ST(2), ST(3), ST(4), ST(5), ST(6), ST(7)

XMM registers

XMM(0), XMM(1), XMM(2), XMM(3), XMM(4), XMM(5), XMM(6), XMM(7)

XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7

ASM supports these special words

PowerBASIC supports three special reserved words, which are used to specify a return value from a procedure of the same type:

FUNCTION | ASM mov FUNCTION, eax
METHOD | ASM mov METHOD, 3
PROPERTY | ASM mov PROPERTY, dx

The above examples are the functional equivalent of the comparable BASIC syntax:

FUNCTION = x&

METHOD = 3

PROPERTY = z%

The exception is that the assembler syntax allows you to assign a return value directly from an appropriate CPU register. Of course, these special reserved words may only be referenced within a procedure of the same type (FUNCTION may only be used in a user-defined function, etc.)

See Also | #ALIGN, ASMDATA/END ASMDATA