CN102937894A - Method for realizing simple and transplantable printf function - Google Patents

Abstract

The invention discloses a method for realizing a simple and transplantable printf function. The method comprises the following steps: (1) defining a send buffer print_buf with N bytes in a stack; (2) outputting content needing to be formatted to the buffer print_buf by a library function sprintf function; and (3) outputting data in the buffer print_buf by a sendString function sending strings. According to the method for realizing the simple and transplantable printf function, the function of macro definition is used, and the existing system library function sprintf is utilized to simplily realize the printf function. Practice indicates that the method can be compatible with the printf function and is transplantable.

Description

A kind of method that realizes the Formatting Output letter function that is simple and easy to transplant

Technical field

The present invention relates to the computer system development method, relate in particular to a kind of method that realizes the Formatting Output letter function that is simple and easy to transplant.

Background technology

Formatting Output function (printf function) be computer system especially the most frequently used in the process of embedded system exploitation, also be one of most important built-in function, the printf function is used for to control desk (screen, serial ports, telnet port or JTAG debug terminal) type information, is one of built-in function the most frequently used in the system debug process.

The prototype of printf function is int printf (char*format, [argument ... ]), wherein format is the form of user's appointment, and argument is the variable of fixed qty not, and argument is the types such as integer, floating number, character string.

The printf function is used for the output Debugging message; be convenient to debugging person and check system's operation information; in embedded system development or migration process; the printf function uses system's built-in function usually; the built-in printf function of system can print to the output control desk of system default usually; if other output control desks that debugging person wishes to export often need function to be redirected or to transplant the Formatting Output function of other functions, understand like this that there are the following problems:

(1) the redirected rule of the different debugging software functions of different platform or identical platform is inconsistent, and the function redirection function even is not provided, and causes transplanting difficulty;

(2) if oneself realizes the printf function performance, often can only realize fairly simple Formatting Output function, as supporting to print integer, character string, do not support long shaping, floating number, the title of function can not be printf, other names can only be changed into, the system transplantation difficulty can be caused equally.

In sum, the printf function often can cause transplanting loaded down with trivial details in embedded systems debugging, the problems such as exploitation difficulty.

Summary of the invention

Goal of the invention: in order to overcome the deficiencies in the prior art, the invention provides a kind of method that realizes the Formatting Output letter function that is simple and easy to transplant, utilize macro definition and existing system library function sprintf function,

Technical scheme: for achieving the above object, the technical solution used in the present invention is:

A kind of method that realizes the Formatting Output letter function that is simple and easy to transplant comprises the steps:

(1) at the transmission buffer zone print_buf of a N byte of storehouse definition;

The content that (2) will need to format by built-in function sprintf function outputs in the buffer zone print_buf;

(3) by the data in the function sendString function output buffer print_buf that sends character string.

Preferably, the size of described buffer zone print_buf can be adjusted as required, generally can be designed as 1024 bytes, i.e. N=1024.

In the said method, the prototype of sprintf function is int sprintf (char*buffer, const char*format, [argument] ...), wherein buffer is the buffer zone of Store form character string, format is the form of user's appointment, and argument is the variable of fixed qty not, and argument is the types such as integer, floating number, character string; The sendString function is the function that system sends character string, can be self-defined by the developer.The method has been carried out macro definition one time, during use this macro definition is placed in the library file, makes to comprise this library file in the source file and get final product.

Beneficial effect: a kind of method that realizes the Formatting Output letter function that is simple and easy to transplant provided by the invention, use the macro definition function, utilize existing system built-in function sprintf, very simply realized the printf function, practice shows, the method can compatible printf function, and be easy to transplant.

Embodiment

Below in conjunction with example the present invention is further described.

A kind of method that realizes the Formatting Output letter function that is simple and easy to transplant comprises the steps:

(1) at the transmission buffer zone print_buf of 1024 bytes of storehouse definition;

The content that (2) will need to format by built-in function sprintf function outputs in the buffer zone print_buf;

(3) by the data in the function sendString function output buffer print_buf that sends character string.

Can realize said method by following program language:

The said procedure language is ingenious utilize do while (0) structure, system library function sprintf function, macro definition function, variadic macros (...), in the macro definition _ _ the VA_ARGS__ key word, realized the printf repertoire, in actual use, can carry out very easily system transplantation and debugging.

Printf is as follows such as system call:

The above only is preferred implementation of the present invention; be noted that for those skilled in the art; under the prerequisite that does not break away from the principle of the invention, can also make some improvements and modifications, these improvements and modifications also should be considered as protection scope of the present invention.

Claims (2)

1. the method for the realization Formatting Output letter function that is simple and easy to transplant is characterized in that: comprise the steps:

(1) at the transmission buffer zone print_buf of a N byte of storehouse definition;

The content that (2) will need to format by built-in function sprintf function outputs in the buffer zone print_buf;

(3) by the data in the function sendString function output buffer print_buf that sends character string.

2. the method for the realization according to claim 1 Formatting Output letter function that is simple and easy to transplant is characterized in that: described N=1024.