Using Inline Assembly Code (Win32 Only)

The built-in assembler allows you to write assembly code within Delphi programs. The inline assembler is available only on the Win32 Delphi compiler. It has the following features:

Allows for inline assembly.
Supports all instructions found in the Intel Pentium 4, Intel MMX extensions, Streaming SIMD Extensions (SSE), and the AMD Athlon (including 3D Now!).
Provides no macro support, but allows for pure assembly function procedures.
Permits the use of Delphi identifiers, such as constants, types, and variables in assembly statements.

As an alternative to the built-in assembler, you can link to object files that contain external procedures and functions. See the topic on External declarations for more information. If you have external assembly code that you want to use in your applications, you should consider rewriting it in the Delphi language or minimally reimplement it using the inline assembler.

Using the asm Statement

The built-in assembler is accessed through asm statements, which have the form

Copy Code

asm statementList end

where statementList is a sequence of assembly statements separated by semicolons, end-of-line characters, or Delphi comments.

Comments in an asm statement must be in Delphi style. A semicolon does not indicate that the rest of the line is a comment.

The reserved word inline and the directive assembler are maintained for backward compatibility only. They have no effect on the compiler.

Using Registers

In general, the rules of register use in an asm statement are the same as those of an external procedure or function. An asm statement must preserve the EDI, ESI, ESP, EBP, and EBX registers, but can freely modify the EAX, ECX, and EDX registers. On entry to an asm statement, EBP points to the current stack frame and ESP points to the top of the stack. Except for ESP and EBP, an asm statement can assume nothing about register contents on entry to the statement.