pdm: Fix error handling around PDM to PCM with verilator

1 files changed, 19 insertions, 1 deletions

diff --git a/bindings/sim_cic3_pdm.cc b/bindings/sim_cic3_pdm.cc
index 323b2dd..9b2b18e 100644
--- a/bindings/sim_cic3_pdm.cc
+++ b/bindings/sim_cic3_pdm.cc
@@ -1,6 +1,7 @@
 
 #include <cstdint>
 #include <cstdio>
+#include <stdexcept>
 
 #include "Vcic3_pdm.h"
 #include "verilated.h"
@@ -8,6 +9,12 @@
 int
 pdm2pcm_cic3(const uint8_t *pdm, int64_t pdm_length, int16_t *pcm, int32_t pcm_length, uint8_t hpf_alpha, uint8_t scale_shift)
 {
+    const int DECIMATION = 64;
+    
+    const int expect_length = pdm_length / DECIMATION; 
+    if (pcm_length < expect_length) {
+        throw std::runtime_error("PCM buffer too small");
+    }
 
 	// FIXME: verify that output buffer is large enough
 
@@ -32,6 +39,7 @@ pdm2pcm_cic3(const uint8_t *pdm, int64_t pdm_length, int16_t *pcm, int32_t pcm_l
 
 	// Go through all the input data
 	int pcm_sample = 0;
+    bool last_valid = top->pcm_valid;
 
 	for (int i = 0; i < pdm_length; i++) {
 
@@ -39,13 +47,23 @@ pdm2pcm_cic3(const uint8_t *pdm, int64_t pdm_length, int16_t *pcm, int32_t pcm_l
 		top->clk = 1;
 		top->eval();
 
-		if (top->pcm_valid) {
+        if (pcm_sample >= pcm_length) {
+            throw std::runtime_error("PCM buffer overrun: pcm_sample=" + std::to_string(pcm_sample) + " pdm_sample="+std::to_string(i));
+        }
+        const bool valid = top->pcm_valid;
+        // && (!last_valid);
+		if (valid) {
 			pcm[pcm_sample++] = top->pcm_out;
 		}
+        last_valid = top->pcm_valid;
 
 		top->clk = 0;
 		top->eval();
 	}
 
+    if (pcm_sample != expect_length) {
+        throw std::runtime_error("Wrong length. expected="+std::to_string(expect_length) + std::string(" got=")+std::to_string(pcm_sample));
+    }
+
 	return pcm_sample;
 }