[Share]sdcc toolchain support

icewalker

dwin released some C51 source codes for T5L core, in order to work with Keil developemnt tool. but I choose to use sdcc. After reading the source codes for Keil c51. I figured out only a few changes can make sdcc work as well.

1. put DWINT5 to the right place. I get this done by assmbly code. I put following code into T5L.as and link it to my firmware.

1. .area CSEG (abs, CODE)
   
2. .org 0xf8
   
3. .globl __T5L_init__
   
4. __T5L_init__: .db 0xff, 0xff
   
5.               .db 'D','W','I','N','T','5'

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2. make sure initialize the registers at the beginning of the "main" function.
   

1.         CKCON = 0x00;
   
2.         T2CON = 0x70;
   
3.         DPC = 0x00;
   
4.         PAGESEL = 0x01;
   
5.         D_PAGESEL = 0x02; //DATA RAM  0x8000-0xFFFF
   
6.         MUX_SEL = 0x00;   //UART2,UART3关闭，WDT关闭
   
7.         RAMMODE = 0x00;

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3.   make sure the linker included following options: --xram-loc 0x8000 --xram-size 0x7fff.
      because the external ram starts from 0x8000 to 0xffff, only 32k, not 65k.

4.   the sdcc has different mcs51 extentions vs Keil.   
      for example, all the keywords __xdata, __data, __sfr. everything has "__" as prefix. I have to go through all the SFR definitions to replace the Keil style with sdcc style.

Keil is the best 8051 compiler, but sdcc still works and free.

DWIN-ARK

Dear，thank you for sharing your experience.