[FreeRTOS源码]vListInitialise函数的反汇编代码阅读

vListInitialise函数

typedef struct xLIST
{
    volatile UBaseType_t uxNumberOfItems;
    ListItem_t * configLIST_VOLATILE pxIndex;
    MiniListItem_t xListEnd;
} List_t;

struct xLIST_ITEM
{
    configLIST_VOLATILE TickType_t xItemValue;
    struct xLIST_ITEM * configLIST_VOLATILE pxNext;
    struct xLIST_ITEM * configLIST_VOLATILE pxPrevious;
    void * pvOwner;
    struct xLIST * configLIST_VOLATILE pxContainer;
};

typedef struct xLIST_ITEM ListItem_t;
typedef struct xLIST_ITEM MiniListItem_t;


void vListInitialise( List_t * const pxList )
{
    /* The list structure contains a list item which is used to mark the
     * end of the list.  To initialise the list the list end is inserted
     * as the only list entry. */
    pxList->pxIndex = ( ListItem_t * ) &( pxList->xListEnd ); /*lint !e826 !e740 !e9087 The mini list structure is used as the list end to save RAM.  This is checked and valid. */

    /* The list end value is the highest possible value in the list to
     * ensure it remains at the end of the list. */
    pxList->xListEnd.xItemValue = portMAX_DELAY;

    /* The list end next and previous pointers point to itself so we know
     * when the list is empty. */
    pxList->xListEnd.pxNext = ( ListItem_t * ) &( pxList->xListEnd );
    pxList->xListEnd.pxPrevious = ( ListItem_t * ) &( pxList->xListEnd );

    pxList->uxNumberOfItems = ( UBaseType_t ) 0U;
}

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字节	[24:21]	[23:20]	[19:16]	[15:12]	[11:8]	[7:4]	[3:0]
基地址偏移				+ C	+ 8	+ 4	+ 0
变量名	pxContainer	pvOwner	pxPrevious	pxNext	xItemValue	pxIndex	uxNumberOfItems

vListInitialise函数汇编

; 无优化 -O0
; void __fastcall vListInitialise(List_t *const pxList)
    SUB      sp,sp,#4            ;栈减1，存放局部变量temp1
    STR      r0,[sp,#0]            ;将R0值存放到temp1(即 pxList)
    ; 
    LDR      r1,[sp,#0]            ;令R1 = temp1
    ADD      r0,r1,#8            ;令R0 = R1 + 8
    STR      r0,[r1,#4]            ;将R0值保存到(R1 + 4)的地址中
    LDR      r1,[sp,#0]            ;
    
    ; 
    ; pxList->xListEnd.xItemValue = portMAX_DELAY;
    MOV      r0,#0xffffffff
    STR      r0,[r1,#8]
    
    LDR      r1,[sp,#0]
    ADD      r0,r1,#8
    STR      r0,[r1,#0xc]
    LDR      r1,[sp,#0]
    ADD      r0,r1,#8
    STR      r0,[r1,#0x10]
    LDR      r1,[sp,#0]
    ; pxList->uxNumberOfItems = ( UBaseType_t ) 0U;
    MOVS     r0,#0
    STR      r0,[r1,#0]
    ; 
    ADD      sp,sp,#4
    BX       lr
    MOVS     r0,r0
    
; 最大优化 -Ofast
; void __fastcall vListInitialise(List_t *const pxList)

    MOV      r1,#0xffffffff     ;令R0 = 0xffffffff
    MOV      r2,r0                 ;将R2赋值pxList地址
    
    STR      r1,[r2,#8]!         ;将R1的值保存到(R2 + 8)的地址中
    MOVS     r1,#0                 ;令R1为0
    STR      r2,[r0,#4]         ;将R2保存到(R0+4)地址中
    
    STRD     r2,r2,[r0,#0xc]    ;将R2分别保存到地址(R0 + 0xC)和(R0 + 0xC + 4)中
    STR      r1,[r0,#0]            ;将R1保存到(R0)地址中
    
    BX       lr                    ;返回
    MOVS     r0,r0                ;

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