补第十章的第三部分“10.5 内存保护单元（MPU）的固件库函数”样例

平湖秋月

补第十章的第三部分“10.5 内存保护单元（MPU）的固件库函数”样例 [复制链接]

下面的示例设置了一组基本的保护区域：

n  在闪存中，一个28 KB区域的只读代码执行

n  在特权和用户模式下32 KB的RAM读写访问

n  仅使用在特权模式下一个额外的8 KB RAM

n  只能在特权模式下访问的1 MB外设空间，除了一个128kb的孔不可访问,另一个128 kb的区域,可以从用户模式访问

以下翻译略-----
//

// Define a 28-KBregion of flash from 0x00000000 to 0x00007000. The

// region isexecutable, and read-only for both privileged and user

// modes. To set upthe region, a 32-KB region (#0) is defined

// starting ataddress 0, and then a 4 KB hole removed at the end by

// disabling thelast sub-region. The region is initially enabled.

//

MPURegionSet(0, 0,

                     MPU_RGN_SIZE_32K |

                     MPU_RGN_PERM_EXEC |

                    MPU_RGN_PERM_PRV_RO_USR_RO |

                    MPU_SUB_RGN_DISABLE_7 |

                    MPU_RGN_ENABLE);

//

// Define a 32-KBregion (#1) of RAM from 0x20000000 to 0x20008000. The

// region is notexecutable, and is read/write access for

// privileged anduser modes.

//

MPURegionSet(1,0x20000000,

                     MPU_RGN_SIZE_32K |

                     MPU_RGN_PERM_NOEXEC |

                     MPU_RGN_PERM_PRV_RW_USR_RW |

                     MPU_RGN_ENABLE);

//

// Define anadditional 8-KB region (#2) in RAM from 0x20008000 to

// 0x2000A000 thatis read/write accessible only from privileged

// mode. This regionis initially disabled, to be enabled later.

//

MPURegionSet(2,0x20008000,

                     MPU_RGN_SIZE_8K |

                     MPU_RGN_PERM_NOEXEC |

                     MPU_RGN_PERM_PRV_RW_USR_NO|

                     MPU_RGN_DISABLE);

//

// Define a region(#3) in peripheral space from 0x40000000 to 0x40100000

// (1 MB). Thisregion is accessible only in privileged mode. There is

// an area from0x40020000 to 0x40040000 that has no peripherals and is not

// accessible atall. This inaccessible region is created by disabling the

// secondsub-region(1) and creating a hole. Further, there is an area

// from 0x40080000to 0x400A0000 that should be accessible from user mode

// as well. Thisarea is created by disabling the fifth sub-region (4),

// and overlaying anadditional region (#4) in that space with the

// appropriatepermissions.

//

MPURegionSet(3,0x40000000,

                     MPU_RGN_SIZE_1M |

                     MPU_RGN_PERM_NOEXEC |

                     MPU_RGN_PERM_PRV_RW_USR_NO |

                     MPU_SUB_RGN_DISABLE_1 | MPU_SUB_RGN_DISABLE_4 |

                     MPU_RGN_ENABLE);

MPURegionSet(4,0x40080000,

                     MPU_RGN_SIZE_128K |

                     MPU_RGN_PERM_NOEXEC |

                     MPU_RGN_PERM_PRV_RW_USR_RW |

                     MPU_RGN_ENABLE);

//

// In this example,compile-time registration of interrupts is used, so the

// handler does nothave to be registered. However, it must be enabled.

//

IntEnable(FAULT_MPU);

//

// When setting upthe regions, region 2 was initially disabled for some

// reason. At somepoint it must be enabled.

//

MPURegionEnable(2);

//

// Now the MPU isenabled. It is configured so that a default

// map is availablein privileged mode if no regions are defined. The MPU

// is not enabledfor the hard fault and NMI handlers, meaning that a

// default is notused whenever these handlers are active, effectively

// giving the faulthandlers access to all of memory without any

// protection.

//

MPUEnable(MPU_CONFIG_PRIV_DEFAULT);

//

// At this point,the MPU is configured and enabled and if any code causes

// an accessviolation, the memory management fault occurs.

//

The followingexample shows how to save and restore region configurations.

//

// The followingarrays provide space for saving the address and

// attributes for 4region configurations.

//

uint32_tui32RegionAddr[4];

uint32_tui32RegionAttr[4];

...

//

// At some point inthe system code, we want to save the state of 4 regions

// (0-3).

//

for(ui8Idx = 0;ui8Idx < 4; ui8Idx++)

{

MPURegionGet(ui8Idx,&ui32RegionAddr[ui8Idx], &ui32RegionAttr[ui8Idx]);

}

...

//

// At some otherpoint, the previously saved regions should be restored.

//

for(ui8Idx = 0;ui8Idx < 4; ui8Idx++)

{

MPURegionSet(ui8Idx,ui32RegionAddr[ui8Idx], ui32RegionAttr[ui8Idx]);

}

[ 本帖最后由 平湖秋月 于 2013-8-19 20:18 编辑 ]

qinkaiabc

请问新书什么时候出版啊？

lskam123

你好，是否可以提供MPU固件的源码