masm中以字母开头的十六进制值 [英] hexadecimal values in masm starting with a letter

问题描述

masm中的十六进制值是否必须以数字开头?如果我使用

Do hexadecimal values in masm have to start with a number? If I use

.const

    _mmx_cons   QWORD f000000000000000h

我收到一个构建错误:

test.asm(26): error A2006: undefined symbol : f000000000000000h

但是如果我添加前导0

But if I add a leading 0

.const

    _mmx_cons   QWORD 0f000000000000000h

该错误消失.这是为什么?我确定它代表64位值0xf000000000000000吗?

The error vanish. Why is that? Am I sure that it represents the 64 bit value 0xf000000000000000?

推荐答案

使用h后缀的十六进制数字必须以十进制数字开头，否则它们将被误认为标签名称.这就是为什么如果最高有效十六进制数字为A .. F.

Hex numbers using the h suffix must start with a decimal digit, otherwise they would be mistaken for label names. That's why you add a leading zero if the most significant hex digit is A..F.

前导零不会影响立即数的值或存储大小要求.例如，写MOV AL, 00000001h完全可以，因为00000001h与1完全相同.

Leading zeroes do not affect the value or storage size requirement of the immediate. For example, it's perfectly ok to write MOV AL, 00000001h, because 00000001h is exactly the same as 1.

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