Unicode to GBK and gnk to Unicode, solving the problem of Rom occupation by fatfs Chinese code table

I have been using the KB Rom stm32, but I only recently used kb. I want to use fatfs to display the support for long file names. I found that the Rom is not enough after cc936.c is added, it is decided to store this two-way code table in external memory, flash or SD card, only can read;

Encoding conversion function in cc936.c after modification
Wchar ff_convert (/* converted code, 0 means Conversion error */
Wchar SRC,
/* Character code to be converted */
Uint dir
/* 0: Unicode to oemcp, 1: oemcp to Unicode */
)
{
Wchar C;

If (SRC <0x80 ){
/* ASCII */
C = SRC;
}
Else
{
If (DIR)
{/* Oemcp to Unicode */

C = gbktounicode (SRC );
}
Else
{/* Unicode to oemcp */
; C = unicodetogbk (SRC );
}
}

Return C;
}

After deleting the two code tables, the Code instantly decreases by several hundred kb.

// I am using w25x16
// Storage location description
// 0x00 ~ 0xbc00
Storage
Utog. sys 42kb
// 0xc000 ~
0x17c00
Store gtou. sys
47kb
// 0x18000 ~
0xd3800 Storage
12x12. TTF 750kb
// 0xd3c00 ~
0x18f400 Storage
16x16. TTF 750kb

// Base address of each file
# Define code_utog_base (0x00)
// Unicode to GBK code table
# Define code_gtou_base (0xc000)
// GBK to Unicode code table
# Define font_12x12_base (0x18000)
// 12x12gbk font
# Define font_16x16_base (0xd3c00)
// 16x16gbk font

The following describes the implementation methods of these two functions.

/*************************************** **************************************** **************************************** **
* Function:
2010gbktounicode (2010gbkcode)
* Function:
Convert GBK encoding to unicode encoding
* Parameters:
GBK
* Return value:
Unicode
* Dependency:
Underlying read/write Functions
* Author:
Chen Peng
* Time:
20120602
* Last modification time: 20120602
* Note: Support for code tables in Flash is required.
GBK code range, 8-bit high: 0x81 ~ 0xfe; low 8 bits: 0x40 ~ 0xfe
**************************************** **************************************** **************************************** */
2010gbktounicode (2010gbkcode)
{
2010unicode;
U8 buff [2];
2010* P;
U8 CH, Cl;

Ch = gbkcode> 8;
CL = gbkcode & 0x00ff;

// Calculate the offset
If (CL <0x7f)
Unicode = (ch-0x81) * 190 + cl-0x40;
If (Cl> 0x80)
Unicode = (ch-0x81) * 190 + cl-0x41;
Unicode * = 2;

W25x16_read (buff, code_gtou_base + Unicode, 2); // read the code table

P = (2010*) Buff;
Return * P;
}

/*************************************** **************************************** **************************************** **
* Function:
Unicodetogbk (UNICODE)
* Function:
Convert Unicode to GBK Encoding
* Parameters:
Unicode
* Return value:
GBK
* Dependency:
Underlying read/write Functions
* Author:
Chen Peng
* Time:
20120602
* Last modification time: 20120602
* Note: Support for code tables in Flash is required.
GBK code range, 8-bit high: 0x81 ~ 0xfe; low 8 bits: 0x40 ~ 0xfe
**************************************** **************************************** **************************************** */
Unicodetogbk (UNICODE) // use a Binary Search Algorithm
{
U32 offset;
U8 temp [2];
2010res;
If (UNICODE <= 0x9fa5) offset = unicode-0X4E00;
Else if (UNICODE> 0x9fa5) // is a punctuation mark
{
If (UNICODE <0xff01 | Unicode> 0xff61) return 0; // no corresponding Encoding
Offset = unicode-0XFF01 + 0x9fa6-0x4e00;
}
W25x16_read (temp, offset * 2 + code_utog_base, 2); // obtain the GBK code
Res = temp [0];
Res <= 8;
Res + = temp [1];
 
Return res; // return the encoding found.
}

You only need to change the underlying IO Interface w25x16_read () based on your memory.