auto import from //depot/cupcake/@135843

1 files changed, 76 insertions, 0 deletions

diff --git a/hash.c b/hash.c
new file mode 100644
index 0000000..e2cffcc
--- /dev/null
+++ b/hash.c
@@ -0,0 +1,76 @@
+#include <common.h>
+#include <debug.h>
+#include <libelf.h>
+#include <hash.h>
+#include <string.h>
+
+void setup_hash(Elf_Data *hash_data,
+                Elf32_Word nbuckets,
+                Elf32_Word nchains)
+{
+    hash_data->d_size  = 2;
+    hash_data->d_size += nbuckets;
+    hash_data->d_size += nchains;
+    hash_data->d_buf   = CALLOC(hash_data->d_size, sizeof(Elf32_Word));
+    hash_data->d_size *= sizeof(Elf32_Word);
+    ((Elf32_Word *)hash_data->d_buf)[0] = nbuckets;
+    ((Elf32_Word *)hash_data->d_buf)[1] = nchains;
+}
+
+void add_to_hash(Elf_Data *hash_data,
+                 const char *symbol,
+                 int symindex)
+{
+    Elf32_Word *buckets  = (Elf32_Word *)hash_data->d_buf;
+    Elf32_Word nbuckets  = *buckets++;
+    Elf32_Word *chains   = ++buckets + nbuckets;
+    Elf32_Word last_chain_index;
+    unsigned long bucket = elf_hash(symbol) % nbuckets;
+
+    ASSERT(symindex != STN_UNDEF);
+
+    if (buckets[bucket] == STN_UNDEF) {
+        INFO("Adding [%s] to hash at bucket [%ld] (first add)\n",
+             symbol, bucket);
+        buckets[bucket] = symindex;
+    }
+    else {
+        INFO("Collision on adding [%s] to hash at bucket [%ld]\n", 
+             symbol, bucket);
+        last_chain_index = buckets[bucket];
+        while (chains[last_chain_index] != STN_UNDEF) {
+            INFO("\ttrying at chain index [%d]...\n", last_chain_index);
+            last_chain_index = chains[last_chain_index];
+        }
+        INFO("\tsuccess at chain index [%d]...\n", last_chain_index);
+        chains[last_chain_index] = symindex;
+    }
+}
+
+int hash_lookup(Elf *elf, 
+                section_info_t *hash_info,
+                section_info_t *symtab_info,
+                const char *symname,
+                GElf_Sym *sym_mem)
+{
+    Elf32_Word *hash_data = (Elf32_Word *)hash_info->data->d_buf;
+    Elf32_Word index;
+    Elf32_Word nbuckets = *hash_data++;
+    Elf32_Word *buckets = ++hash_data;
+    Elf32_Word *chains  = hash_data + nbuckets;
+
+    GElf_Sym *sym;
+
+    index = buckets[elf_hash(symname) % nbuckets];
+    while(index != STN_UNDEF)
+    {
+        sym = gelf_getsymshndx (symtab_info->data, NULL, index, sym_mem, NULL);
+        FAILIF_LIBELF(NULL == sym, gelf_getsymshndx);
+        if (!strcmp(symname,
+                    elf_strptr(elf, symtab_info->hdr->sh_link, sym->st_name))) 
+            break;
+        index = chains[index];
+    }
+
+    return index;
+}