如何在C中返回此数组asm函数的值?在这种情况下,我不确定如何使用sprintf。
我需要在显示中显示数组函数之前和之后的一些值。
//*****************************************************************************
//FUNCTION: InitXa
//DESCRIPTION: array X of size N with a constant value V, using pointers:
//PARAMETERS: r0 = *X
// r1 = Size N
// r2 = Value V
//RETURN: None
//*****************************************************************************
// local register definitions
#define rXA r0 // register to hold address of X
#define rN r1 // register to hold value of N
#define rV r2 // register to hold value of V
__asm void InitXa (uint32 *X, uint32 N, uint32 V)
{
STR rN, [rXA] ; Store the value at first address of array.
SUBS rV, #1 ; decrement the count
loop
STR rN,[rXA],#4 ; Store the value and increment the pointer
SUBS rV,rV,#1 ; decrement the count
BNE loop ; branch until the count is 0
BX lr ; return to caller
}
C部分代码:
uint32 X = {10, 2, 3};
uint32 N = 10;
uint32 V = 3;
uint32 result32;
sprintf (str, "%d", result32); // **display the first few values of the array before initialization on the top line of the OLED.**
InitXa (X, N, V);
sprintf (str, "%d", result32); //**Use the second line to display values after** initialization.
答案 0 :(得分:0)
您似乎不熟悉如何访问数组元素。此外,未使用result32值,因此无需打印它。我认为这就是你的意图:
printf("Before calling asm function: %d, %d, %d \n", X[0], X[1], X[2]);
InitXa (X, N, V);
printf("After calling asm function: %d, %d, %d \n", X[0], X[1], X[2]);
写作风格相当干燥,但它帮助我理解了30年前的C并且它今天同样有效。