c_sample\u​sertypes/u​sertypes.h​(10) : error C2371: 'sint16' : redefinition; different basic types

Hi, I am new to s-functions. And I am trying to write s-function using basic c mex s-function template. I am getting this error, "c_sample\usertypes/usertypes.h(10) : error C2371: 'sint16' : redefinition; different basic types" and other errors as well. I have attached the files in .zip format. Please help resolve the issue.

I would like to understand how to include multiple .c and .h files while writing handwritten c mex s-functions.

Note: tools used are Matlab2016b and compiler is windows sdk 7.1

Please consider c_sample_4.zip file for files (syntax errors are removed). But still getting below erros.

>> mex c_sample_4_sfun.c

Building with 'Microsoft Windows SDK 7.1 (C)'.

Error using mex

c_sample_4_sfun.c

d:\new folder\c_sample_4\common\../usertypes/usertypes.h(10) : error C2371: 'ft_sint16' : redefinition; different basic types

d:\new folder\c_sample_4\common\../usertypes/usertypes.h(7) : see declaration of 'ft_sint16'

d:\new folder\c_sample_4\common\../usertypes/usertypes.h(11) : error C2371: 'ft_uint16' : redefinition; different basic types

d:\new folder\c_sample_4\common\../usertypes/usertypes.h(8) : see declaration of 'ft_uint16'

d:\new folder\c_sample_4\menu\menu.h(4) : error C2146: syntax error : missing ')' before identifier 'arg_a'

d:\new folder\c_sample_4\menu\menu.h(4) : error C2061: syntax error : identifier 'arg_a'

d:\new folder\c_sample_4\menu\menu.h(4) : error C2059: syntax error : ';'

d:\new folder\c_sample_4\menu\menu.h(4) : error C2059: syntax error : ','

d:\new folder\c_sample_4\menu\menu.h(4) : error C2059: syntax error : ')'

d:\new folder\c_sample_4\menu\../multiplication/multiplication_interface.h(4) : error C2061: syntax error : identifier 'multiplication'

d:\new folder\c_sample_4\menu\../multiplication/multiplication_interface.h(4) : error C2059: syntax error : ';'

d:\new folder\c_sample_4\menu\../multiplication/multiplication_interface.h(4) : error C2059: syntax error : 'type'

d:\new folder\c_sample_4\menu/menu.c(8) : error C2061: syntax error : identifier 'output_mult'

d:\new folder\c_sample_4\menu/menu.c(8) : error C2059: syntax error : ';'

d:\new folder\c_sample_4\menu/menu.c(8) : error C2513: '/*global*/ ' : no variable declared before '='

d:\new folder\c_sample_4\menu/menu.c(19) : error C2065: 'output_mult' : undeclared identifier

d:\new folder\c_sample_4\menu/menu.c(19) : warning C4013: 'multiplication' undefined; assuming extern returning int

D:\New folder\c_sample_4\c_sample_4_sfun.c(157) : error C2100: illegal indirection

D:\New folder\c_sample_4\c_sample_4_sfun.c(158) : error C2100: illegal indirection

D:\New folder\c_sample_4\c_sample_4_sfun.c(163) : error C2065: 'output_mult' : undeclared identifier

**************************************