How to build with subdirectories

I created a dsp/delay folder in the root directory and created delay.cpp in it.
How do I set up MakeFile to include this and build it?
project_root/
├── Makefile
├── MutliBoxDSP.cpp
└── dsp/
└── delay/
Delay.h
Delay.cpp
rtwtypes.h

dsp/delay/Delay.h:26:10: fatal error: dsp/delay/rtwtypes.h: No such file or directory
26 | #include “dsp/delay/rtwtypes.h”

# Project Name
TARGET = MutltiBoxDSP

USE_DAISYSP_LGPL = 0
# Sources
CPP_SOURCES += MutltiBoxDSP.cpp \
dsp/delay/Delay.cpp \

# Library Locations
LIBDAISY_DIR = ../../libDaisy/
DAISYSP_DIR = ../../DaisySP/
LDFLAGS = -u _printf_float

CPPFLAGS += -I$(DAISYSP_DIR)/dsp/delay
CPPFLAGS += -Idsp/delay

# Core location, and generic Makefile.
SYSTEM_FILES_DIR = $(LIBDAISY_DIR)/core
include $(SYSTEM_FILES_DIR)/Makefile

MutltiBoxDSP.zip (410.6 KB)

Hi
It looks like your archive is missing the files “tmwtypes.h” and “simstruc_types.h”. Additionally, you need to add "${workspaceFolder}/dsp/delay" in your c_cpp_properties.json file.

Philippe