add hash

1 files changed, 36 insertions, 0 deletions

diff --git a/twasm/asm/main.asm b/twasm/asm/main.asm
index 1ed4932..7262a8f 100644
--- a/twasm/asm/main.asm
+++ b/twasm/asm/main.asm
@@ -1446,6 +1446,42 @@ elemb:
     ret
 
 ; ------------------------------------------------------------------------------
+; djb2
+;
+; description:
+; gets the djb2 hash of a given string
+;
+; parameters:
+; rdi = size of string
+; rsi -> start of string
+;
+; returned:
+; rax = hash
+; ------------------------------------------------------------------------------
+
+djb2:
+  xor ecx, ecx  ; rcx = index
+  mov rax, 5381 ; rax = hash
+
+  .loop:
+    cmp rcx, rdi
+    jge .break
+
+    mov rdx, rax
+    shl rax, 5
+    add rax, rdx
+
+    xor edx, edx
+    mov dl, [rsi + rcx] ; dl = current byte
+    add rax, rdx
+
+    inc rcx
+    jmp .loop
+
+  .break:
+    ret
+
+; ------------------------------------------------------------------------------
 ; trim_trailing_whitespace
 ;
 ; description: