From 1969b6c40bb4cf99f5034deb957e330920397e9c Mon Sep 17 00:00:00 2001
From: ame <grantsquires@disroot.org>
Date: Tue, 26 Mar 2024 13:03:34 -0500
Subject: docs and rolling adler

---
 src/hash/adler.c | 52 ++++++++++++++++++++++++++++++++++++++++++++--------
 src/hash/adler.h | 20 ++++++++++++--------
 2 files changed, 56 insertions(+), 16 deletions(-)

(limited to 'src/hash')

diff --git a/src/hash/adler.c b/src/hash/adler.c
index 3bd865a..ed7a84e 100644
--- a/src/hash/adler.c
+++ b/src/hash/adler.c
@@ -2,15 +2,50 @@
 #include <stdio.h>
 #include <stdint.h>
 
-uint32_t i_adler32(uint8_t *aa, size_t len){
-    uint16_t a = 1, b = 0;
+struct adler32_hash adler32_init(){
+  return (struct adler32_hash){.a = 1, .b = 0};
+}
+
+void adler32_update(uint8_t* aa, size_t len, struct adler32_hash* hash){
+  for(int i = 0; i != len; i++){
+    hash->a += aa[i];
+    hash->b += hash->a;
+  }
+}
+
+uint32_t adler32_final(struct adler32_hash* hash){
+  return hash->b * 65536 + hash->a;
+}
+
+uint32_t adler32(uint8_t* aa, size_t len){
+  struct adler32_hash dig = adler32_init();
+  adler32_update(aa, len, &dig);
+  return adler32_final(&dig);
+}
+
+int l_adler32_init(lua_State* L){
+  struct adler32_hash* a = (struct adler32_hash*)lua_newuserdata(L, sizeof * a);
+  *a = adler32_init();
+  return 1;
+}
 
-    for(int i = 0; i != len; i++){
-        a += aa[i];
-        b += a;
-    }
+int l_adler32_update(lua_State* L){
+  struct adler32_hash* a = (struct adler32_hash*)lua_touserdata(L, 1);
+  size_t len = 0;
+  uint8_t* b = (uint8_t*)luaL_checklstring(L, 2, &len);
+
+  adler32_update(b, len, a);
+
+  return 1;
+}
 
-    return b * 65536 + a;
+int l_adler32_final(lua_State* L){
+  struct adler32_hash* a = (struct adler32_hash*)lua_touserdata(L, 1);
+  uint32_t u = adler32_final(a);
+  char digest[32];
+  sprintf(digest,"%08x",u);
+  lua_pushstring(L, digest);
+  return 1;
 }
 
 int l_adler32(lua_State* L){
@@ -19,7 +54,8 @@ int l_adler32(lua_State* L){
   
   char digest[32];
 
-  uint32_t u = i_adler32(a, len);
+  uint32_t u = adler32(a, len);
+
   sprintf(digest,"%08x",u);
   lua_pushstring(L, digest);
 
diff --git a/src/hash/adler.h b/src/hash/adler.h
index 3bd8925..29a74f0 100644
--- a/src/hash/adler.h
+++ b/src/hash/adler.h
@@ -1,13 +1,17 @@
 #include "../lua.h"
 #include <stdint.h>
 
-/*!
- * \brief calculates a adler hash of (len) bytes
- *
- * @param {uint8_t*} input bytes
- * @param {size_t} input length
- * @return {uint32_t} 32 bit hash
-*/
-uint32_t i_adler32(uint8_t*, size_t);
+struct adler32_hash {
+  uint16_t a;
+  uint16_t b;
+};
+
+struct adler32_hash adler32_init();
+void adler32_update(uint8_t*, size_t, struct adler32_hash*);
+uint32_t adler32_final(struct adler32_hash*);
+uint32_t adler32(uint8_t*, size_t);
 
 int l_adler32(lua_State*);
+int l_adler32_init(lua_State*);
+int l_adler32_update(lua_State*);
+int l_adler32_final(lua_State*);
-- 
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