add hash

twasm/asm/main.asm

@@ -1445,6 +1445,42 @@ elemb:
     mov rax, 1 ; return 1; dl an element of list
     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
 ;

twasm/asm/tests.asm

@@ -13,6 +13,9 @@ run_tests:
   mov rsi, .msg
   call print.test
 
+  call clear_test_arena
+  call test_djb2
+
   call clear_test_arena
   call test_elemb
 
@@ -109,6 +112,68 @@ test_elemb:
   .case1 db 0x54, 0x00, 0x21, 0x20, 0x34
   .msg db "test_elemb...", 0x00
 
+; ------------------------------------------------------------------------------
+; test_djb2
+;
+; description:
+; tests djb2 described functionality
+; ------------------------------------------------------------------------------
+
+test_djb2:
+  mov rsi, .msg
+  call print.test
+
+  mov rsi, .case0
+  mov rdi, 0
+  call djb2
+  cmp rax, 5381
+  jne .fail
+
+  mov rsi, .case1
+  mov rdi, 1
+  call djb2
+  cmp rax, 177670
+  jne .fail
+
+  mov rsi, .case2
+  mov rdi, 2
+  call djb2
+  cmp rax, 5863208
+  jne .fail
+
+  ; why am I testing this, of course it's without side effects xD
+
+  mov rsi, .case0
+  mov rdi, 0
+  call djb2
+  cmp rax, 5381
+  jne .fail
+
+  mov rsi, .case1
+  mov rdi, 1
+  call djb2
+  cmp rax, 177670
+  jne .fail
+
+  mov rsi, .case2
+  mov rdi, 2
+  call djb2
+  cmp rax, 5863208
+  jne .fail
+
+  .pass:
+    mov rsi, msg_pass
+    call print
+    ret
+  .fail:
+    mov rsi, msg_fail
+    call print
+    ret
+  .case0 db ""
+  .case1 db "a"
+  .case2 db "ab"
+  .msg db "test_djb2...", 0x00
+
 ; ------------------------------------------------------------------------------
 ; test_get_tte_type
 ;