文件开头的静态和非静态变量定义区别

Question

Looking at an ST example file for one of its devices.

On the same .c file there are different definitions.

Curious to know what might be the reason for some of the definitions to be static and some not.

PLACE_IN_SECTION("BLE_DRIVER_CONTEXT") static tListNode HciAsynchEventQueue; // static

PLACE_IN_SECTION("BLE_DRIVER_CONTEXT") static TL_CmdPacket_t *pCmdBuffer; // static

PLACE_IN_SECTION("BLE_DRIVER_CONTEXT") HCI_TL_UserEventFlowStatus_t UserEventFlow; // not static

All appear at the top of the file . One after another. All are used inside the file only.

Answer 1

static file level (global) variables do not have external linkage and will not be seen from other compilation units (more simple files). They have the same storage duration as non static variables but their "visibility" is limited to one compilation unit (source file).