From 36c17d22d0b6c99dd7b55d8606eea1d9ffb3a9d1 Mon Sep 17 00:00:00 2001
From: adamdunkels <adamdunkels>
Date: Thu, 15 Mar 2007 21:38:46 +0000
Subject: [PATCH] uIP checksum calculation for MSP430

---
 cpu/msp430/uip-ipchksum.c | 28 ++++++++++++++++++++++++++++
 1 file changed, 28 insertions(+)
 create mode 100644 cpu/msp430/uip-ipchksum.c

diff --git a/cpu/msp430/uip-ipchksum.c b/cpu/msp430/uip-ipchksum.c
new file mode 100644
index 000000000..d401a261a
--- /dev/null
+++ b/cpu/msp430/uip-ipchksum.c
@@ -0,0 +1,28 @@
+/*---------------------------------------------------------------------------*/
+#ifdef UIP_ARCH_IPCHKSUM
+u16_t
+uip_ipchksum(void)
+{
+  /* Assumes proper alignement of uip_buf. */
+  u16_t *p = (u16_t *)&uip_buf[UIP_LLH_LEN];
+  register u16_t sum;
+
+  sum = p[0];
+  asmv("add  %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[1]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[2]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[3]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[4]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[5]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[6]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[7]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[8]));
+  asmv("addc %[p], %[sum]": [sum] "+r" (sum): [p] "m" (p[9]));
+
+  /* Finally, add the remaining carry bit. */
+  asmv("addc #0, %[sum]": [sum] "+r" (sum));
+
+  /* Return sum in network byte order. */
+  return (sum == 0) ? 0xffff : sum;
+}
+#endif
+/*---------------------------------------------------------------------------*/