Runtime Lookup Table Updates - 2025.2 English

When TP_USE_LUT_RELOAD = 1, lookup tables can be modified at runtime via RTP ports instead of being fixed at compile time.

RTP Port Configuration:

• Two RTP ports are created for parallel memory access
• Both ports must be updated with identical lookup table data

Runtime Update Methods:

There are two methods for update of LUT values at runtime:

1. Use the provided graph update_rtp function. This will perform all required duplication and broadcast.
2. Drive data to the graph RTP ports directly. In this case, data must be duplicated depending on device as described below, and must be broadcast to both ports.

Graph Instantiation:

// Static LUT (TP_USE_LUT_RELOAD = 0)
std::array<TT_LUT, kLutValues> staticLUT = { /* values */ };
func_approx_graph<TT_DATA, TP_COARSE_BITS, ...> graph(staticLUT);

// Runtime LUT (TP_USE_LUT_RELOAD = 1)
func_approx_graph<TT_DATA, TP_COARSE_BITS, ..., 1> graph(); // No LUT argument

Runtime Updates:

std::array<TT_LUT, kLutValues> newLUT = { /* new values */ };
graph.update_rtp(topGraph, newLUT, graph.rtpLut);

Memory Duplication Requirements:

For AIE-ML and AIE-MLv2 devices with int16 or bfloat16 data types, hardware parallel access requires memory duplication:

// Memory layout for AIE-ML (128-bit alignment)
// Each group of 8 entries (slope-offset pairs) is duplicated
lut_data = {s0,o0, s1,o1, s2,o2, s3,o3,    // First 128-bit block
            s0,o0, s1,o1, s2,o2, s3,o3,    // Duplicated block
            s4,o4, s5,o5, s6,o6, s7,o7,    // Second 128-bit block
            s4,o4, s5,o5, s6,o6, s7,o7,    // Duplicated block
            ...}

// Memory layout for AIE-MLv2 (256-bit alignment)
// Each group of 16 entries is duplicated
lut_data = {s0,o0, s1,o1, ..., s7,o7,      // First 256-bit block
            s0,o0, s1,o1, ..., s7,o7,      // Duplicated block
            s8,o8, s9,o9, ..., s15,o15,    // Second 256-bit block
            s8,o8, s9,o9, ..., s15,o15,    // Duplicated block
            ...}

Automatic Duplication: The update_rtp method handles all duplication automatically.