major restructuring, prepare for smp

code/drivers/net/lwip/include/stdlib.h

@@ -0,0 +1,38 @@
+#pragma once
+#ifndef LWIP_PORT_STDLIB_H
+#define LWIP_PORT_STDLIB_H
+
+/*
+ * Minimal freestanding stdlib shim for lwIP.
+ *
+ * lwIP 2.2.1 includes <stdlib.h> in a couple of files only for atoi().  If MSVC
+ * finds the UCRT header, it drags errno.h into the kernel build and then lwIP's
+ * own errno values collide with UCRT's.  Put this header first in lwIP's include
+ * path so those sources stay freestanding.
+ */
+static __inline int atoi(const char* s) {
+    int sign = 1;
+    int value = 0;
+
+    if (!s)
+        return 0;
+
+    while (*s == ' ' || *s == '\t' || *s == '\n' || *s == '\r' || *s == '\v' || *s == '\f')
+        ++s;
+
+    if (*s == '-') {
+        sign = -1;
+        ++s;
+    } else if (*s == '+') {
+        ++s;
+    }
+
+    while (*s >= '0' && *s <= '9') {
+        value = value * 10 + (*s - '0');
+        ++s;
+    }
+
+    return sign * value;
+}
+
+#endif /* LWIP_PORT_STDLIB_H */