first commit

port/sys_arch.c

@@ -0,0 +1,25 @@
+#include "ch32fun.h"
+#include "lwip/def.h"
+#include "systick.h"
+
+typedef uint32_t sys_prot_t;
+static unsigned long next = 1;
+
+int rand(void) {
+  next = next * 1103515245 + 12345;
+  return (unsigned int)(next / 65536) % 32768;
+}
+
+void srand(unsigned int seed) { next = seed; }
+
+uint32_t sys_now(void) { return systick_millis; }
+
+sys_prot_t sys_arch_protect(void) {
+  unsigned int old_mstatus;
+  __asm__ volatile("csrrci %0, mstatus, 8" : "=r"(old_mstatus));
+  return old_mstatus;
+}
+
+void sys_arch_unprotect(sys_prot_t pval) {
+  __asm__ volatile("csrw mstatus, %0" : : "r"(pval));
+}