From e0b68536a5c405e8e028c65c3d4e22b5b99218bd Mon Sep 17 00:00:00 2001
From: jacqueline <me@jacqueline.id.au>
Date: Fri, 14 Oct 2022 14:38:12 +1100
Subject: [PATCH] Use a fixed transaction buffer size

---
 main/i2c.cpp | 10 ++++++++--
 main/i2c.hpp |  1 +
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/main/i2c.cpp b/main/i2c.cpp
index 4ae3b267..9b218f3f 100644
--- a/main/i2c.cpp
+++ b/main/i2c.cpp
@@ -1,16 +1,22 @@
 #include "i2c.hpp"
+#include <cstdint>
 
 #include "assert.h"
+#include "driver/i2c.h"
 
 namespace gay_ipod {
 
 I2CTransaction::I2CTransaction() {
-  handle_ = i2c_cmd_link_create();
+  // Use a fixed size buffer to avoid many many tiny allocations.
+  // TODO: make this static and tune the size. possibly make it optional too?
+  // threading.
+  buffer_ = (uint8_t*) calloc(sizeof(uint8_t), I2C_LINK_RECOMMENDED_SIZE(10));
+  handle_ = i2c_cmd_link_create_static(buffer_, I2C_LINK_RECOMMENDED_SIZE(10));
   assert(handle_ != NULL && "failed to create command link");
 }
 
 I2CTransaction::~I2CTransaction() {
-  i2c_cmd_link_delete(handle_);
+  free(buffer_);
 }
 
 esp_err_t I2CTransaction::Execute() {
diff --git a/main/i2c.hpp b/main/i2c.hpp
index 6b2de577..0993a305 100644
--- a/main/i2c.hpp
+++ b/main/i2c.hpp
@@ -78,6 +78,7 @@ class I2CTransaction {
 
  private:
   i2c_cmd_handle_t handle_;
+  uint8_t *buffer_;
 };
 
 }  // namespace gay_ipod