[英]C/Digital Logic - Why are my zero-initialized variables changing value?
它們實際上被初始化為字符'0'(即48)。 我正在制作一個邏輯模擬器,每個位都表示為一個字符,“0”或“1”。 在我制作了一個 8 位選擇器之前,我所有的其他組件都可以正常工作。
這是 1 位選擇器的代碼。 它工作正常。
typedef char Bit;
...
typedef struct SelectorComp {
Bit store;
Bit data[2];
NandGate nand[3];
NotGate not;
Bit out;
} SelectorComp;
void initSelector(SelectorComp* selector) {
int i;
selector->store = '0';
for (i = 0; i < 2; i++) selector->data[i] = '0';
initNot(&selector->not);
for (i = 0; i < 3; i++) initNand(&selector->nand[i]);
Selector(selector);
}
void Selector(SelectorComp* selector) {
selector->nand[0].in[0] = selector->store;
selector->nand[0].in[1] = selector->data[0];
Nand(&selector->nand[0]);
selector->not.in = selector->store;
Not(&selector->not);
selector->nand[1].in[0] = selector->not.out;
selector->nand[1].in[1] = selector->data[1];
Nand(&selector->nand[1]);
selector->nand[2].in[0] = selector->nand[0].out;
selector->nand[2].in[1] = selector->nand[1].out;
Nand(&selector->nand[2]);
selector->out = selector->nand[2].out;
}
8 位選擇器基本上是 8 個 1 位選擇器捆綁在一起。
typedef struct Selector8Comp {
Bit store;
Bit data[2][8];
SelectorComp selector[8];
Bit out[8];
} Selector8Comp;
void initSelector8(Selector8Comp* selector8) {
int i, j;
selector8->store = '0';
for (i = 0; i < 2; i++) {
for (j = 0; j < 8; j++) {
selector8->data[i][j] = '0';
}
}
for (i = 0; i < 8; i++) initSelector(&selector8->selector[i]);
Selector8(selector8);
}
void Selector8(Selector8Comp* selector8) {
int i, j;
for (i = 0; i < 8; i++) {
selector8->selector[i].store = selector8->store;
for (j = 0; j < 2; j++) selector8->selector[i].data[j] = selector8->data[i][j];
Selector(&selector8->selector[i]);
selector8->out[i] = selector8->selector[i].out;
}
}
但是,當我用下面的 function 測試它時,我得到了意想不到的 output。
void testSelector8() {
int i;
Selector8Comp* selector8 = (Selector8Comp*)malloc(sizeof(Selector8Comp));
initSelector8(selector8);
printf("Testing 8-bit selector\n");
printf("store: %c\n", selector8->store);
printf("byte 0: ");
for (i = 0; i < 8; i++) printf("%c", selector8->data[0][i]);
printf("\nbyte 1: ");
for (i = 0; i < 8; i++) printf("%c", selector8->data[1][i]);
printf("\nselectors:\n");
for (i = 0; i < 8; i++) {
printf("%d: store: %c in: %c%c out: %c\n", i, selector8->selector[i].store, selector8->selector[i].data[0], selector8->selector[i].data[1], selector8->selector[i].out);
}
printf("\noutput: ");
for (i = 0; i < 8; i++) printf("%c", selector8->out[i]);
printf("\n");
free(selector8);
}
預期 output:
store: 0
byte 0: 00000000
byte 1: 00000000
selectors:
0: store: 0 in: 00 out: 0
1: store: 0 in: 00 out: 0
2: store: 0 in: 00 out: 0
3: store: 0 in: 00 out: 0
4: store: 0 in: 00 out: 0
5: store: 0 in: 00 out: 0
6: store: 0 in: 00 out: 0
7: store: 0 in: 00 out: 0
output: 0000000
實際 output:
store: 0
byte 0: 00000000
byte 1: 00000000
selectors:
0: store: 0 in: 00 out: 0
1: store: 0 in: 00 out: 0
2: store: 0 in: 00 out: 0
3: store: 0 in: 11 out: 1
4: store: 0 in: 10 out: 0
5: store: 0 in: 10 out: 0
6: store: 0 in: 01 out: 1
7: store: 0 in: 01 out: 1
output: 00010011
除非我讀錯了我的代碼,否則所有這些選擇器都應該將它們的數據初始化為“00”。 他們為什么不呢?
編輯:如果有幫助,我在 ARM 上使用最新的 gcc。
我讀錯了我的代碼(想象一下)。 我切換了 i 和 aj(Selector8 function 定義的第 5 行)。 在這種情況下, j 應該在 i 之前。
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