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postfix chain

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This commit is contained in:
Yaossg 2024-11-17 10:29:04 +08:00
parent 3910fc3413
commit fc9ac15c4b
2 changed files with 58 additions and 6 deletions
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19
boot.c
View File

@ -249,12 +249,16 @@ void next_token() {
} else if (ch == '/') {
int ch2 = getchar();
if (ch2 == '/') {
while ((ch = getchar()) != '\n');
do ch = getchar(); while (ch != '\n' && ch != -1);
next_token();
return;
} else if (ch2 == '*') {
while (1) {
ch = getchar();
if (ch == -1) {
eprintf("expecting '*/'\n");
exit(1);
}
if (ch == '*') {
ch = getchar();
if (ch == '/') {
@ -773,7 +777,7 @@ int parse_postfix_expr() {
store_t0(reg);
printf(" addi t0, t0, %d\n", step_of(type));
store_t0(lhs);
return reg;
lhs = reg;
} else if (token_type == TOKEN_DEC) {
int type = local_type[lhs];
int reg = next_reg(type);
@ -781,11 +785,11 @@ int parse_postfix_expr() {
store_t0(reg);
printf(" addi t0, t0, -%d\n", step_of(type));
store_t0(lhs);
return reg;
lhs = reg;
} else if (token_type == TOKEN_BRACKET_LEFT) {
int rhs = parse_expr();
expect_token(TOKEN_BRACKET_RIGHT);
return indirection_of(asm_add(lhs, rhs));
lhs = indirection_of(asm_add(lhs, rhs));
} else if (token_type == TOKEN_PAREN_LEFT) {
int arg = 0;
int args[8];
@ -817,13 +821,14 @@ int parse_postfix_expr() {
load_address(0, lhs);
printf(" jalr t0\n");
printf(" mv t0, a0\n");
return materialize_t0(local_type[lhs]);
lhs = materialize_t0(local_type[lhs]);
} else {
unget_token();
break;
}
}
return lhs;
}
}
}
int parse_prefix_expr() {
next_token();

47
demo/queen.c Normal file
View File

@ -0,0 +1,47 @@
int printf(const char format[], ...);
int putchar(int ch);
int a[9];
void output() {
for (int i = 1; i <= 8; ++i) {
for (int j = 1; j <= 8; ++j) {
if (a[i] == j) {
putchar('x');
} else {
putchar('-');
}
}
putchar('\n');
}
putchar('\n');
}
int ok(int x, int y) {
for (int i = 1; i <= x - 1; ++i) {
if (a[i] == y || a[i] - i == y - x || a[i] + i == y + x) {
return 0;
}
}
return 1;
}
void queen(int x) {
if (x > 8) {
output();
a[0]++;
}
for (int y = 1; y <= 8; ++y) {
if (ok(x, y)) {
a[x] = y;
queen(x + 1);
a[x] = 0;
}
}
}
int main() {
queen(1);
printf("solutions: %d\n", a[0]);
return 0;
}