diff --git a/lib_nn/src/asm/lookup8.S b/lib_nn/src/asm/lookup8.S
index a3ab9e00..b9d305bc 100644
--- a/lib_nn/src/asm/lookup8.S
+++ b/lib_nn/src/asm/lookup8.S
@@ -103,5 +103,103 @@ FUNCTION_NAME:
 
 #endif
 
+#if defined(__VX4B__)
+
+/*
+void lookup8_asm(
+    uint8_t* Y,
+    const uint8_t* X,
+    const uint8_t* lut,
+    const unsigned elm_start,
+    const unsigned elm_count);
+*/
+
+#define FUNCTION_NAME lookup8_asm
+
+.p2align 1
+.globl FUNCTION_NAME
+.type FUNCTION_NAME,@function
+
+#define STACK_X18         (0)
+#define STACK_X19         (STACK_X18 + 4)
+#define STACK_X20         (STACK_X19 + 4)
+#define STACK_X21         (STACK_X20 + 4)
+#define STACK_X22         (STACK_X21 + 4)
+#define STACK_X23         (STACK_X22 + 4)
+#define STACK_X24         (STACK_X23 + 4)
+#define STACK_VEC1_TMP    (STACK_X24 + 4)
+#define STACK_RA          (STACK_VEC1_TMP + 32)
+#define NSTACKBYTES       (STACK_RA + 4)
+#define ROUND_UP(X, Y)    (((X+Y-1)/Y)*Y)
+
+#define out_data    x10 
+#define in_data     x11 
+#define lut         x12
+#define start       x13
+#define count       x18
+#define mask        x19
+#define counter     x20
+#define thirty_two  x21
+#define vec1_tmp    x22
+
+FUNCTION_NAME:
+
+    { xm.entsp ROUND_UP(NSTACKBYTES, 16)    ; xm.nop				    }
+    xm.stdsp x18, x19, 0*8
+    xm.stdsp x20, x21, 1*8
+    xm.stdsp x22, x23, 2*8
+    sw x24, 3*8(sp)
+    addi count, x14, 0
+    add out_data, out_data, start
+    add in_data, in_data, start
+    addi vec1_tmp, sp, STACK_VEC1_TMP
+    xm.mkmski mask, 32
+    li thirty_two, 32
+    // out_data substract 32 first for optimize in the loop
+    sub out_data, out_data, thirty_two
+
+    // Set VPU to 8-bit mode
+    li x28, 512
+    { xm.vsetc x28                          ; xm.shri counter, count, 5 }
+    xm.vldc lut
+
+    FUNCTION_NAME.loop:
+        { xm.vldr in_data                   ; add in_data, in_data, thirty_two }
+        xm.vlookup lut, 0, 1
+        xm.vlookup lut, 1, 2
+        xm.vlookup lut, 2, 3
+        xm.vlookup lut, 3, 4
+        xm.vlookup lut, 4, 5
+        xm.vlookup lut, 5, 6
+        xm.vlookup lut, 6, 7
+        xm.vlookup lut, 7, 0
+        bnez counter, FUNCTION_NAME.save
+        // In last loop - make mask for remaining elements
+        xm.zexti count, 4
+        xm.mkmsk mask, count
+
+        FUNCTION_NAME.save:
+            { xm.vstd vec1_tmp                  ; xm.nop                                }
+            { xm.vldr vec1_tmp                  ; add out_data, out_data, thirty_two    }
+            xm.vstrpv out_data, mask
+            { addi counter, counter, -1         ; xm.bt counter, FUNCTION_NAME.loop     }
+
+
+    xm.lddsp x18, x19, 0*8
+    xm.lddsp x20, x21, 1*8
+    xm.lddsp x22, x23, 2*8
+    lw x24, 3*8(sp)
+
+    {xm.retsp ROUND_UP(NSTACKBYTES, 16); xm.nop}
+
+.size FUNCTION_NAME, . -FUNCTION_NAME
+.resource_const FUNCTION_NAME, "stack_frame_bytes",  ROUND_UP(NSTACKBYTES, 16)
+.resource_list_empty FUNCTION_NAME, "callees"
+.resource_list_empty FUNCTION_NAME, "tail_callees"
+.resource_list_empty FUNCTION_NAME, "parallel_callees"
+
+#endif
+
+
 
 
diff --git a/lib_nn/src/c/nn_operator.c b/lib_nn/src/c/nn_operator.c
index c16837d0..0e950dfe 100644
--- a/lib_nn/src/c/nn_operator.c
+++ b/lib_nn/src/c/nn_operator.c
@@ -139,6 +139,15 @@ void lookup8_ref(uint8_t *Y, const uint8_t *X, const uint8_t *lut,
   }
 }
 
+#if defined(__XS3A__) || defined(__VX4B__)
+void lookup8_asm(
+    uint8_t* Y,
+    const uint8_t* X,
+    const uint8_t* lut,
+    const unsigned elm_start,
+    const unsigned elm_count);
+#endif
+
 #ifdef NN_USE_REF
 void requantize_16_to_8(int8_t *y, const int16_t *x, const unsigned elm_start,
                         const unsigned elm_count) {
@@ -148,10 +157,12 @@ void requantize_16_to_8(int8_t *y, const int16_t *x, const unsigned elm_start,
 
 void lookup8(uint8_t *Y, const uint8_t *X, const uint8_t *lut,
              const unsigned elm_start, const unsigned elm_count) {
-#if defined(NN_USE_REF) || defined(__VX4A__) || defined(__VX4B__)
+#if defined(NN_USE_REF)
   lookup8_ref(Y, X, lut, elm_start, elm_count);
-#elif defined(__XS3A__)
+#elif defined(__XS3A__) || defined(__VX4B__)
   lookup8_asm(Y, X, lut, elm_start, elm_count);
+#else
+  lookup8_ref(Y, X, lut, elm_start, elm_count);
 #endif // NN_USE_REF
 }