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doc: 64 bit moffs in the syntax chapter

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Mention 64 bit moffs and link to the section in the 64-bit chapter.

Signed-off-by: Maciej Wieczor-Retman <maciej.wieczor-retman@intel.com>
This commit is contained in:
Maciej Wieczor-Retman
2025-09-29 15:03:46 +02:00
parent 1653419dde
commit 9abbc4aa41
2 changed files with 13 additions and 0 deletions
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4
doc/64bit.src
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@@ -62,6 +62,8 @@ In 64-bit mode, immediates and displacements are generally only 32
bits wide. NASM will therefore truncate most displacements and
immediates to 32 bits.
\S{id64imm} Immediate 64-bit Operands
The only instruction which takes a full \i{64-bit immediate} is:
\c MOV reg64,imm64
@@ -97,6 +99,8 @@ instruction is able to reference a symbol anywhere in the 64-bit
address space, whereas \c{LEA} is only able to access a symbol within
within 2 GB of the instruction itself (see below.)
\S{id64disp} 64-bit Displacements
The only instructions which take a full \I{64-bit displacement}64-bit
\e{displacement} is loading or storing, using \c{MOV}, \c{AL}, \c{AX},
\c{EAX} or \c{RAX} (but no other registers) to an absolute 64-bit address.

9
doc/syntax.src
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@@ -1,5 +1,14 @@
\C{Syntax} Syntax Quirks and Summaries
\H{64moff} 64-bit \i{MOFFS}
The moffs operand can be used with the \c{MOV} instruction, only using the A
register (AL/AH, AX, EAX, RAX), and for non-64-bit operand size means to address
memory at an offset from a segment. For \I{64-bit immediate} 64-bit operands it
simply accesses memory at a specified offset (since segment based addressing is
mostly unavailable in 64-bit mode). Syntax to use 64-bit offsets to address
memory is showcased in \k{id64disp}.
\H{spliteas} \i{Split EA} Addressing Syntax
Instructions that use the mib operand, (that is memory addressed with a base