change(spo2): Allocate buffers on heap

pycardium/modules/spo2_algo.c

@@ -5,10 +5,13 @@
 #include "py/obj.h"
 #include "py/runtime.h"
 
-static mp_obj_t mp_maxim_rd177(mp_obj_t ir, mp_obj_t red)
-{
+struct spo2_memory {
 	uint32_t pun_ir_buffer[500];
 	uint32_t pun_red_buffer[500];
+};
+
+static mp_obj_t mp_maxim_rd177(mp_obj_t ir, mp_obj_t red)
+{
 	int32_t n_ir_buffer_length;
 
 	int32_t pn_spo2       = 0;
@@ -39,16 +42,24 @@ static mp_obj_t mp_maxim_rd177(mp_obj_t ir, mp_obj_t red)
 		);
 	}
 
+	struct spo2_memory *m =
+		(struct spo2_memory *)MP_STATE_PORT(spo2_memory);
+	if (!m) {
+		/* Will raise an exception if out of memory: */
+		m = m_malloc(sizeof(struct spo2_memory));
+		MP_STATE_PORT(spo2_memory) = m;
+	}
+
 	n_ir_buffer_length = ir_len;
 	for (size_t i = 0; i < ir_len; i++) {
-		pun_ir_buffer[i]  = mp_obj_get_int(ir_elem[i]);
-		pun_red_buffer[i] = mp_obj_get_int(red_elem[i]);
+		m->pun_ir_buffer[i]  = mp_obj_get_int(ir_elem[i]);
+		m->pun_red_buffer[i] = mp_obj_get_int(red_elem[i]);
 	}
 
 	maxim_heart_rate_and_oxygen_saturation(
-		pun_ir_buffer,
+		m->pun_ir_buffer,
 		n_ir_buffer_length,
-		pun_red_buffer,
+		m->pun_red_buffer,
 		&pn_spo2,
 		&pch_spo2_valid,
 		&pn_heart_rate,

pycardium/mpconfigport.h

@@ -114,4 +114,5 @@ typedef long mp_off_t;
 #define MICROPY_PORT_ROOT_POINTERS \
     const char *readline_hist[16]; \
     mp_obj_t interrupt_callbacks[EPIC_INT_NUM]; \
+    void *spo2_memory; \