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/* coroutine.c - Simple coroutine and request/response implementation
*
* Copyright (C) 2024 Luke T. Shumaker <lukeshu@lukeshu.com>
* SPDX-Licence-Identifier: AGPL-3.0-or-later
*/
#include <stdlib.h> /* for malloc(pico_malloc) and realloc(pico_malloc) */
#include "coroutine.h"
static cid_t coroutine_table_len = 0;
_cr_entry_t *_coroutine_table = NULL;
cid_t _cur_cid = 0;
void coroutine_init(void) {
if (coroutine_table_len)
return;
coroutine_table_len = 1;
_coroutine_table = malloc(sizeof _coroutine_table[0]);
_coroutine_table[0] = (_cr_entry_t){
.fn = (cr_fn_t)0xDEAD,
.stack = NULL,
.state = 0,
.blocked = true,
};
}
cid_t coroutine_add(cr_fn_t fn, void *stack) {
cid_t cid = 0;
for (cid_t i = 1; cid == 0 && i < coroutine_table_len; i++)
if (_coroutine_table[i].fn == NULL)
cid = i;
if (cid == 0) {
cid = coroutine_table_len++;
_coroutine_table = realloc(_coroutine_table, (sizeof _coroutine_table[0]) * coroutine_table_len);
}
_coroutine_table[cid] = (_cr_entry_t){
.fn = fn,
.stack = stack,
.state = 0,
.blocked = false,
};
return cid;
}
void coroutine_task(void) {
cid_t start = (_cur_cid + 1) % coroutine_table_len;
cid_t shift;
for (shift = 0;
shift < coroutine_table_len &&
(_coroutine_table[(start+shift)%coroutine_table_len].fn == NULL ||
_coroutine_table[(start+shift)%coroutine_table_len].blocked);
shift++) {}
if (shift == coroutine_table_len)
return;
_cur_cid = (start + shift) % coroutine_table_len;
_coroutine_table[_cur_cid].fn(_coroutine_table[_cur_cid].stack);
}
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