boot: Add EFISTUB and refactor boot protocols

boot/loader/lib.c

@@ -0,0 +1,53 @@
+// SPDX-License-Identifier: ISC
+
+#include <stddef.h>
+#include <stdint.h>
+#include <string.h>
+
+size_t strlen(const char* str) {
+    if (!str)
+        return 0;
+
+    size_t len = 0;
+    while (str[len])
+        len++;
+    return len;
+}
+
+int memcmp(const void* s1, const void* s2, size_t size) {
+    const uint8_t* a = s1;
+    const uint8_t* b = s2;
+    for (size_t i = 0; i < size; i++) {
+        if (a[i] != b[i])
+            return a[i] < b[i] ? -1 : 1;
+    }
+    return 0;
+}
+
+void* memcpy(void* restrict dest, const void* restrict src, size_t n) {
+    uint8_t* d = dest;
+    const uint8_t* s = src;
+    for (size_t i = 0; i < n; i++)
+        d[i] = s[i];
+    return dest;
+}
+
+void* memmove(void* dstptr, const void* srcptr, size_t size) {
+    uint8_t* d = dstptr;
+    const uint8_t* s = srcptr;
+    if (d < s) {
+        for (size_t i = 0; i < size; i++)
+            d[i] = s[i];
+    } else {
+        for (size_t i = size; i > 0; i--)
+            d[i - 1] = s[i - 1];
+    }
+    return dstptr;
+}
+
+void* memset(void* dest, int value, size_t n) {
+    uint8_t* d = dest;
+    for (size_t i = 0; i < n; i++)
+        d[i] = (uint8_t)value;
+    return dest;
+}