Initial sysparam implementation

Problems with inability to write individual bytes to flash.  Need to reorganize
to read/write word-multiples instead.

core/include/esp/types.h

@@ -3,6 +3,7 @@
 
 #include <stdint.h>
 #include <stdbool.h>
+#include <stddef.h>
 
 typedef volatile uint32_t *esp_reg_t;
 

core/include/sysparam.h

@@ -0,0 +1,42 @@
+#ifndef _SYSPARAM_H_
+#define _SYSPARAM_H_
+
+#include <esp/types.h>
+
+#ifndef SYSPARAM_REGION_SECTORS
+// Number of (4K) sectors that make up a sysparam region.  Total sysparam data
+// cannot be larger than this.  Note that the actual amount of used flash
+// space will be *twice* this amount.
+#define SYSPARAM_REGION_SECTORS 1
+#endif
+
+typedef struct {
+    char *key;
+    uint8_t *value;
+    size_t key_len;
+    size_t value_len;
+    size_t bufsize;
+    struct sysparam_context *ctx;
+} sysparam_iter_t;
+
+typedef enum {
+    SYSPARAM_ERR_NOMEM   = -5,
+    SYSPARAM_ERR_BADDATA = -4,
+    SYSPARAM_ERR_IO      = -3,
+    SYSPARAM_ERR_FULL    = -2,
+    SYSPARAM_ERR_BADARGS = -1,
+    SYSPARAM_OK          = 0,
+    SYSPARAM_NOTFOUND    = 1,
+} sysparam_status_t;
+
+sysparam_status_t sysparam_init(uint32_t base_addr, bool create);
+sysparam_status_t sysparam_get_raw(const char *key, uint8_t **destptr, size_t *actual_length);
+sysparam_status_t sysparam_get_string(const char *key, char **destptr);
+sysparam_status_t sysparam_get_raw_static(const char *key, uint8_t *buffer, size_t buffer_size, size_t *actual_length);
+sysparam_status_t sysparam_put_raw(const char *key, const uint8_t *value, size_t value_len);
+sysparam_status_t sysparam_put_string(const char *key, const char *value);
+sysparam_status_t sysparam_iter_start(sysparam_iter_t *iter);
+sysparam_status_t sysparam_iter_next(sysparam_iter_t *iter);
+void sysparam_iter_end(sysparam_iter_t *iter);
+
+#endif /* _SYSPARAM_H_ */