summaryrefslogtreecommitdiffstats
path: root/cpukit/libnetworking/netinet/in_cksum_powerpc.h
diff options
context:
space:
mode:
Diffstat (limited to 'cpukit/libnetworking/netinet/in_cksum_powerpc.h')
-rw-r--r--cpukit/libnetworking/netinet/in_cksum_powerpc.h174
1 files changed, 174 insertions, 0 deletions
diff --git a/cpukit/libnetworking/netinet/in_cksum_powerpc.h b/cpukit/libnetworking/netinet/in_cksum_powerpc.h
new file mode 100644
index 0000000000..9de5a95e35
--- /dev/null
+++ b/cpukit/libnetworking/netinet/in_cksum_powerpc.h
@@ -0,0 +1,174 @@
+/*
+ * Checksum routine for Internet Protocol family headers.
+ *
+ * This routine is very heavily used in the network
+ * code and should be modified for each CPU to be as fast as possible.
+ *
+ * This implementation is the PowerPC version.
+ *
+ * $Id$
+ */
+
+#include <stdio.h> /* for puts */
+
+#undef ADDCARRY
+#define ADDCARRY(x) if ((x) > 0xffff) (x) -= 0xffff
+#define REDUCE {sum = (sum & 0xffff) + (sum >> 16); ADDCARRY(sum);}
+
+/*
+ * Thanks to gcc we don't have to guess
+ * which registers contain sum & w.
+ */
+
+#define LDTMP(n) tmp = *((u_int *)((u_char *)w + n))
+
+#define ADD(n) \
+ LDTMP(n); \
+ __asm__ volatile("addc %0,%0,%2" : "=r" (sum) : "0" (sum), "r" (tmp))
+
+#define ADDC(n) \
+ LDTMP(n); \
+ __asm__ volatile("adde %0,%0,%2" : "=r" (sum) : "0" (sum), "r" (tmp))
+
+#define MOP \
+ tmp = 0; \
+ __asm__ volatile("adde %0,%0,%2" : "=r" (sum) : "0" (sum), "r" (tmp))
+
+#define LOAD(n) junk = (u_char) *((volatile u_char *) w + n)
+
+
+int
+in_cksum(
+ struct mbuf *m,
+ int len
+)
+{
+ u_char junk;
+ register u_short *w;
+ register unsigned sum = 0;
+ register unsigned tmp;
+ register int mlen = 0;
+ int byte_swapped = 0;
+ union { char c[2]; u_short s; } su;
+
+ for (;m && len; m = m->m_next) {
+ if (m->m_len == 0)
+ continue;
+ w = mtod(m, u_short *);
+ if (mlen == -1) {
+ /*
+ * The first byte of this mbuf is the continuation
+ * of a word spanning between this mbuf and the
+ * last mbuf.
+ */
+
+ /* su.c[0] is already saved when scanning previous
+ * mbuf. sum was REDUCEd when we found mlen == -1
+ */
+ su.c[1] = *(u_char *)w;
+ sum += su.s;
+ w = (u_short *)((char *)w + 1);
+ mlen = m->m_len - 1;
+ len--;
+ } else
+ mlen = m->m_len;
+ if (len < mlen)
+ mlen = len;
+ len -= mlen;
+ /*
+ * Force to long boundary so we do longword aligned
+ * memory operations
+ */
+ if (3 & (int) w) {
+ REDUCE;
+ if ((1 & (int) w) && (mlen > 0)) {
+ sum <<= 8;
+ su.c[0] = *(char *)w;
+ w = (u_short *)((char *)w + 1);
+ mlen--;
+ byte_swapped = 1;
+ }
+ if ((2 & (int) w) && (mlen >= 2)) {
+ sum += *w++;
+ mlen -= 2;
+ }
+ }
+
+ /*
+ * Do as much of the checksum as possible 32 bits at at time.
+ * In fact, this loop is unrolled to keep overhead from
+ * branches small.
+ */
+ while (mlen >= 32) {
+ /*
+ * Add with carry 16 words and fold in the last
+ * carry by adding a 0 with carry.
+ *
+ * The early ADD(16) and the LOAD(32) are intended
+ * to help get the data into the cache.
+ */
+ ADD(16);
+ ADDC(0);
+ ADDC(4);
+ ADDC(8);
+ ADDC(12);
+ LOAD(32);
+ ADDC(20);
+ ADDC(24);
+ ADDC(28);
+ MOP;
+ w += 16;
+ mlen -= 32;
+ }
+ if (mlen >= 16) {
+ ADD(0);
+ ADDC(4);
+ ADDC(8);
+ ADDC(12);
+ MOP;
+ w += 8;
+ mlen -= 16;
+ }
+ if (mlen >= 8) {
+ ADD(0);
+ ADDC(4);
+ MOP;
+ w += 4;
+ mlen -= 8;
+ }
+ if (mlen == 0 && byte_swapped == 0)
+ continue; /* worth 1% maybe ?? */
+ REDUCE;
+ while ((mlen -= 2) >= 0) {
+ sum += *w++;
+ }
+ if (byte_swapped) {
+ sum <<= 8;
+ byte_swapped = 0;
+ if (mlen == -1) {
+ su.c[1] = *(char *)w;
+ sum += su.s;
+ mlen = 0;
+ } else
+ mlen = -1;
+ } else if (mlen == -1)
+ /*
+ * This mbuf has odd number of bytes.
+ * There could be a word split betwen
+ * this mbuf and the next mbuf.
+ * Save the last byte (to prepend to next mbuf).
+ */
+ su.c[0] = *(char *)w;
+ }
+
+ if (len)
+ puts("cksum: out of data");
+ if (mlen == -1) {
+ /* The last mbuf has odd # of bytes. Follow the
+ standard (the odd byte is shifted left by 8 bits) */
+ su.c[1] = 0;
+ sum += su.s;
+ }
+ REDUCE;
+ return (~sum & 0xffff);
+}