strchr

lang/src/lib.asm

@@ -187,6 +187,46 @@ memcpy:
 .done:
     ret
 
+;; Returns a pointer to the first occurrence of c in s, or null if not found
+;; rdi: pointer to byte slice
+;; rsi: length of byte slice
+;; dl: byte to find
+;; fn strchr(s: &[u8], c: u8) -> &[u8]
+strchr:
+    ; if s.len() == 0 {
+    test rsi, rsi
+    ;   return &[];
+    je .null
+    ; } else {
+    xor r8, r8
+    ;   for i in 0..s.len() {
+.loop:
+    cmp r8, rsi
+    jge .null
+    ;     if s[i] == c {
+    mov al, [rdi + r8]
+    cmp al, dl
+    ;       return &s[i..];
+    je .found
+    ;     }
+    inc r8
+    ;   }
+    jmp .loop
+    ; }
+.null:
+    xor rax, rax
+    xor rdx, rdx
+    ret
+.found:
+    add rdi, r8
+    mov rax, rdi
+    mov rdx, rsi
+    sub rdx, r8
+    ret
+    
+
+    
+
 section .rdata
     e_is_dir db "Is a directory", 10
     e_is_dir_len equ $ - e_is_dir