fix: sync Yosys-compatible packed LLR interface from chip_ignite

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

rtl/ldpc_decoder_top.sv

@@ -15,7 +15,6 @@ module ldpc_decoder_top #(
     parameter Z         = 32,       // lifting factor
     parameter N         = N_BASE * Z, // codeword length = 256
     parameter K         = Z,        // info bits = 32 (rate 1/8)
-    parameter M         = M_BASE * Z, // parity checks = 224
     parameter Q         = 6,        // LLR quantization bits (signed)
     parameter MAX_ITER  = 30,       // maximum decoding iterations
     parameter DC        = 8,        // check node degree (= N_BASE for regular)
@@ -50,8 +49,8 @@ module ldpc_decoder_top #(
     logic        stat_converged;
     logic [4:0]  stat_iter_used;
 
-    // LLR input buffer (written by host before starting decode)
-    logic signed [Q-1:0] llr_input [N];
+    // LLR input buffer (packed vector for Yosys compatibility)
+    logic [N*Q-1:0] llr_input_flat;
 
     // Decoded output
     logic [K-1:0]  decoded_bits;
@@ -75,7 +74,7 @@ module ldpc_decoder_top #(
         .stat_busy      (stat_busy),
         .stat_converged (stat_converged),
         .stat_iter_used (stat_iter_used),
-        .llr_input      (llr_input),
+        .llr_input      (llr_input_flat),
         .decoded_bits   (decoded_bits),
         .syndrome_weight(syndrome_weight),
         .irq_o          (irq_o)
@@ -99,7 +98,7 @@ module ldpc_decoder_top #(
         .start          (ctrl_start),
         .early_term_en  (ctrl_early_term),
         .max_iter       (ctrl_max_iter),
-        .llr_in         (llr_input),
+        .llr_in         (llr_input_flat),
         .busy           (stat_busy),
         .converged      (stat_converged),
         .iter_used      (stat_iter_used),