CX51 用户手册----ROM伪指令_#pragma rom ( large )-优快云博客

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ROM Compiler Directive

Abbreviation

None.

Arguments

(SMALL), (COMPACT), (LARGE), (D512K), or (D16M)

Default

ROM (LARGE)

µVision

Options — Target — Code ROM Size.

Description

You use the ROM directive to specify the size of the program memory. This directive affects the coding of the JMP and CALL instructions.

Option	Description
SMALL	CALL and JMP instructions are coded as ACALL and AJMP. The maximum program size may be 2 KBytes. The entire program must be allocated within the 2 KByte program memory space.
COMPACT	CALL instructions are coded as LCALL. JMP instructions are coded asAJMP within a function. The size of a function must not exceed 2 KBytes. The entire program may, however, comprise a maximum of 64 KBytes. The type of application determines whether or not ROM (COMPACT) is more advantageous than ROM (LARGE). Any code space saving advantages in using ROM (COMPACT) must be empirically determined.
LARGE	CALL and JMP instructions are coded as LCALL and LJMP. This allows you to use the entire address space without any restrictions. Program size is limited to 64 KBytes. Function size is also limited to 64 KBytes.
D512K† (Dallas 390& variants)	19-bit ACALL and AJMP instructions are generated. The maximum program size may be 512 KBytes. This mode is available only for the Dallas 390 and compatible devices.
D16M† (Dallas 390& variants)	24-bit LCALL instructions and 19-bit AJMP instructions are generated. The maximum program size may be 16MBytes. This mode is available only for the Dallas 390 and compatible devices.

Note

缩写

无。

参数

(SMALL), (COMPACT), (LARGE), (D512K), or (D16M)

缺省

ROM (LARGE)

µVision

Options — Target — Code ROM Size.

描述

用户指定 ROM 伪指令指定程序存储器的大小。这个伪指令影响JMP 和 CALL 指令的代码。

Option	Description
SMALL	CALL 和 JMP 指令编码为 ACALL 和 AJMP. 最大的程序代码为 2 K字节。整个程序必须分配在 2 K字节的程序存储器空间。
COMPACT	CALL 指令编码为 LCALL. JMP 编码为AJMP 。函数的大小不能超过2 K字节。但是整个程序最大到64 K字节。应用程序的类型决定 ROM (COMPACT) 是否比 ROM (LARGE)更有利。使用 ROM (COMPACT) 节省代码的优势必须根据经验决定。
LARGE	CALL 和 JMP 指令编码为 LCALL 和 LJMP。这允许用户没有如何限制地使用这个地址空间。程序大小限制在64 K字节，函数大小也限制在64 K字节。
D512K† (Dallas 390& variants)	生成19-bit ACALL和 AJMP 指令。最大的程序大小为 512 K字节。这个模式只对Dallas 390 和兼容器件有效。
D16M† (Dallas 390& variants)	生成24-bit LCALL 指令和 19-bit AJMP 指令。最大的程序大小为 16M字节。这个模式只对 Dallas 390 和兼容器件有效。

注意

参考

示例

C51 SAMPLE.C ROM (SMALL)

#pragma ROM (SMALL)