extmod/modlwip: Initial commit of the lwip network stack module

extmod/lwip-include/arch/cc.h

+#ifndef __CC_H__
+#define __CC_H__
+
+#include <stdint.h>
+
+// Generate lwip's internal types from stdint
+
+typedef uint8_t u8_t;
+typedef int8_t s8_t;
+typedef uint16_t u16_t;
+typedef int16_t s16_t;
+typedef uint32_t u32_t;
+typedef int32_t s32_t;
+
+typedef u32_t mem_ptr_t;
+
+#define U16_F "hu"
+#define S16_F "hd"
+#define X16_F "hx"
+#define U32_F "u"
+#define S32_F "d"
+#define X32_F "x"
+
+#define X8_F  "02x"
+#define SZT_F "u"
+
+#define BYTE_ORDER LITTLE_ENDIAN
+
+#define LWIP_CHKSUM_ALGORITHM 2
+
+#include <assert.h>
+#define LWIP_PLATFORM_DIAG(x)
+#define LWIP_PLATFORM_ASSERT(x)  { assert(1); }
+
+//#define PACK_STRUCT_FIELD(x) x __attribute__((packed))
+#define PACK_STRUCT_FIELD(x) x
+#define PACK_STRUCT_STRUCT __attribute__((packed))
+#define PACK_STRUCT_BEGIN
+#define PACK_STRUCT_END
+
+#endif /* __ARCH_CC_H__ */

extmod/lwip-include/arch/perf.h

+#ifndef __PERF_H__
+#define __PERF_H__
+
+#define PERF_START    /* null definition */
+#define PERF_STOP(x)  /* null definition */
+
+#endif /* __PERF_H__ */

extmod/lwip-include/lwipopts.h

+#ifndef __LWIPOPTS_H__
+#define __LWIPOPTS_H__
+
+// We're running without an OS for this port. We don't provide any services except light protection.
+#define NO_SYS 1
+
+#define SYS_LIGHTWEIGHT_PROT 1
+#include <stdint.h>
+typedef uint32_t sys_prot_t;
+
+#define TCP_LISTEN_BACKLOG 1
+
+// We'll put these into a proper ifdef once somebody implements an ethernet driver
+#define LWIP_ARP 0
+#define LWIP_ETHERNET 0
+
+#define LWIP_DNS 1
+
+#define LWIP_NETCONN 0
+#define LWIP_SOCKET 0
+
+#ifdef MICROPY_PY_LWIP_SLIP
+#define LWIP_HAVE_SLIPIF 1
+#endif
+
+// For now, we can simply define this as a macro for the timer code. But this function isn't
+// universal and other ports will need to do something else. It may be necessary to move
+// things like this into a port-provided header file.
+#define sys_now HAL_GetTick
+
+#endif
+