Difficult between atmega328 & atmega2560 when coding & compiling in a pure c I have an arduino uno with atmega328p controller.

I found the code to deal with some specific uart protocol, named mdb: https://github.com/Bouni/MateDealer/tree/master/arduino

But it's compiled just for atmega2560 controller: https://github.com/Bouni/MateDealer/blob/master/arduino/makefile#L42

If I replace it by atmega328p or atmega328, I get the error:

asiniy@misha:~/projects/MateDealer/arduino$ make all

-------- begin --------
avr-gcc (GCC) 4.8.2
Copyright (C) 2013 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.


Compiling: main.c
avr-gcc -c -mmcu=atmega328 -I. -gdwarf-2   -Os -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes -Wa,-adhlns=main.lst  -std=gnu99 -DF_OSC=16000000 -MD -MP -MF .dep/main.o.d main.c -o main.o

Compiling: usart.c
avr-gcc -c -mmcu=atmega328 -I. -gdwarf-2   -Os -funsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -Wall -Wstrict-prototypes -Wa,-adhlns=usart.lst  -std=gnu99 -DF_OSC=16000000 -MD -MP -MF .dep/usart.o.d usart.c -o usart.o
usart.c:25:40: error: ‘UBRR1H’ undeclared here (not in a function)
     { { { {}, 0, 0 }, { {}, 0, 0 } }, &amp;UBRR1H, &amp;UBRR1L, &amp;UCSR1B, &amp;UCSR1C },
                                        ^
usart.c:25:49: error: ‘UBRR1L’ undeclared here (not in a function)
     { { { {}, 0, 0 }, { {}, 0, 0 } }, &amp;UBRR1H, &amp;UBRR1L, &amp;UCSR1B, &amp;UCSR1C },
                                                 ^
usart.c:25:58: error: ‘UCSR1B’ undeclared here (not in a function)
     { { { {}, 0, 0 }, { {}, 0, 0 } }, &amp;UBRR1H, &amp;UBRR1L, &amp;UCSR1B, &amp;UCSR1C },
                                                          ^
usart.c:25:67: error: ‘UCSR1C’ undeclared here (not in a function)
     { { { {}, 0, 0 }, { {}, 0, 0 } }, &amp;UBRR1H, &amp;UBRR1L, &amp;UCSR1B, &amp;UCSR1C },
                                                                   ^
In file included from usart.c:14:0:
usart.c: In function ‘USART0_RX_vect’:
usart.c:185:5: warning: ‘USART0_RX_vect’ appears to be a misspelled signal handler [enabled by default]
 ISR(USART0_RX_vect){
     ^
usart.c: In function ‘USART1_RX_vect’:
usart.c:197:5: warning: ‘USART1_RX_vect’ appears to be a misspelled signal handler [enabled by default]
 ISR(USART1_RX_vect){
     ^
usart.c:203:12: error: ‘UDR1’ undeclared (first use in this function)
     data = UDR1;
            ^
usart.c:203:12: note: each undeclared identifier is reported only once for each function it appears in
In file included from usart.c:14:0:
usart.c: In function ‘USART0_UDRE_vect’:
usart.c:233:5: warning: ‘USART0_UDRE_vect’ appears to be a misspelled signal handler [enabled by default]
 ISR(USART0_UDRE_vect){
     ^
usart.c: In function ‘USART1_UDRE_vect’:
usart.c:253:5: warning: ‘USART1_UDRE_vect’ appears to be a misspelled signal handler [enabled by default]
 ISR(USART1_UDRE_vect){
     ^
usart.c:261:31: error: ‘TXB81’ undeclared (first use in this function)
                 UCSR1B |= (1&lt;&lt;TXB81);
                               ^
usart.c:266:9: error: ‘UDR1’ undeclared (first use in this function)
         UDR1 = data;
         ^
usart.c:269:20: error: ‘UDRIE1’ undeclared (first use in this function)
     UCSR1B &amp;= ~(1&lt;&lt;UDRIE1);
                    ^
make: *** [usart.o] Error 1


I've tried to play with compilers (default is gnu99) and so on, but with no success. Why I have this trouble? How can I compile this code for upload it to arduino?
I'm the author of the MateDealer project and I never had the intention to port it to other boards than the Arduino Mega2560! 

Ignacio Vazquez-Abrams is absolutely right, the Arduino Mega2560 is the only board with more than 1 serial port (Yes there is the Due and the Leonardo, but those would require major changes to the code).

The fastest way to get the code running is by using a Mega2560, but be warned, the code might be bugy as hell ;-)