/*!
    \file    readme.txt
    \brief   description of flash secure mark region configuration example with TZEN=1

    \version 2021-10-30, V1.0.0, firmware for GD32W51x
*/

/*
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*/

  This example is based on the GD32W515P-EVAL-V1.0 board, the project consists of 
two sub-projects, secure project and nonsecure project. It shows how to switch from 
secure application to non-secure application, and call secure functions in nonsecure
application. The fmc_secmark_region_disable function is defined in non-secure callable 
area in secure application, and is called by nonsecure application. 
  The system always starts from the secure application, and the secure application is
responsible for starting the nonsecure application.Therefore, in the compilation process,
first compile the secure project, and then compile the nonsecure project.
  Before downloading the program, the option byte needs to be configured as follows: 
    1.enable trustzone
        TZEN = 1
    2.configure secure mark pages
        FMC_SECMCFG0 = 0x003F0000
        startpage :0x00  endpage:0x3F  means that the first 64 pages of flash are configured
        as secure
In secure application,the program execution follows the following steps:
    1.configre SAU/IDAU, FPU and secure/nosecure interrupts allocations in 
    partition_gd32w51x.h file the key configuration is as follows:
        Enable SAU
        SAU Region 0  start address: 0x0C03E000  end address: 0x0C03FFFF  Attributes: S/NSC
        SAU Region 1  start address: 0x08040000  end address: 0x081FFFFF  Attributes: NS
        SAU Region 2  start address: 0x20010000  end address: 0x2001FFFF  Attributes: NS
        SAU Region 3  start address: 0x40000000  end address: 0x4FFFFFFF  Attributes: NS
    2.configure TZBMPC
        TZBMPC1 vector register y(y=0 to 7):0x00000000 means that SRAM1(64KB) are configured
        as nonsecure
    3.Configure secure mark pages : page128~page130
    4.Erase and program secure flash page128~page130 and check whether the secure flash memory 
has been correctly programmed. If the result is right, LED1 will be on. 
    5.Configure and jump to non-secure application
 
In non-secure Application :
    1.Read the secure pages and check whether it is RAZ. If all read data is 0, light the 
LED2. 
    2.Call the NSC function to disable the page128~page130 security, read the same area and check 
whether the read data is the secure application programming data. If it is, light the LED3.