// cpu header file, contains variable declarations, short definition macros, and bitmasks that
// are declared for clarity and ease of use; macros that do real work can be found in actions.h

/* UART Transmit variables and definitions */
#pragma regalloc-				// don't want to store declared variables in registers
unsigned char txc_buffer1[80];	// write from here to transmit buffer, alternate 1 and 2 for simultaneous read and write
unsigned char txc_buffer2[80];	// write from here to transmit buffer, alternate 1 and 2 for simultaneous read and write
unsigned char buf_index;      	// tracks which byte in the txc_buffer we are writing from
unsigned char trans_done;        // indicates whether the transmitter is idle
unsigned char* txc_write_buffer; // pointer to the buffer to transmit from (to send to outside world)
unsigned char* txc_read_buffer;  // pointer to the buffer transmit data can be written to if transmitter is busy (from code, waiting to be sent)
unsigned char* buffer_switch;    // temp pointer used to switch txc_write_buffer and txc_read_buffer
unsigned char write_ready;       // indicates another set of data is ready to be sent
unsigned char temp_buffer[80];	 // temporary uses such as storing the string to print out to serial

/* UART receive variables */
char rxc_done;         // indicates whether we are done receiving (whether user has hit enter)
char r_index;          // index of rxc_buffer
unsigned char r_char;  // current received character

// Define 6502 registers, working variables, sreg flag masks for assembly use
#asm
; define 6502 registers for ASM
.def REG_SR=r19
.def REG_A=r8
.def REG_X=r2
.def REG_Y=r3
.def REG_IR=r4
.def REG_SP=r5
.def REG_PCL=r12
.def REG_PCH=r13

; define working variables for ASM
.def REG_OP=r9
.def REG_OPADDRL=r10
.def REG_OPADDRH=r11
.def REG_TMP=r16                ;note: can only perform immediate operations on r16-31
.def REG_TMP2=r17
.def REG_TMP3=r18
.def REG_TMP4=r20

; define 6502 status register flags (bit masks)
.equ ASR_N=0x80
.equ ASR_V=0x40
.equ ASR_B=0x10
.equ ASR_D=0x08
.equ ASR_I=0x04
.equ ASR_Z=0x02
.equ ASR_C=0x01

; bit order of the status flags in the 6502 sreg
.equ ASR_NB=7
.equ ASR_VB=6
.equ ASR_BB=4
.equ ASR_DB=3
.equ ASR_IB=2
.equ ASR_ZB=1
.equ ASR_CB=0

; inverted bit mask
.equ ASR_NI=0x7f
.equ ASR_VI=0xbf
.equ ASR_BI=0xef
.equ ASR_DI=0xf7
.equ ASR_II=0xfb
.equ ASR_ZI=0xfd
.equ ASR_CI=0xfe
#endasm

#pragma regalloc-

// define 6502 registers for C use (allocate the registers such that they
// "overlap" and thus are the same as the ones declared for ASM use).
// note: only able to allocate a variable to a register to when
// the register number is <= 15.
register unsigned char	rA	@ 0x08;
register unsigned char	rX	@ 0x02;
register unsigned char	rY	@ 0x03;
register unsigned char	rIR	@ 0x04;
register unsigned char	rSP	@ 0x05;
register unsigned int	rPC	@ 0x0C;
register unsigned char	rPCL	@ 0x0C;
register unsigned char	rPCH	@ 0x0D;

// define general working register definitions for use in C; again we overlap
// with the same register numbers as declared for ASM use
// note: can't allocate any variables to reg16-31
register unsigned char operand @ 0x09;
register unsigned int op_addr @ 0x0A;

// define 6502 status register flags for C
#define SR_N (rSR.7)
#define SR_V (rSR.6)
#define SR_B (rSR.4)
#define SR_D (rSR.3)
#define SR_I (rSR.2)
#define SR_Z (rSR.1)
#define SR_C (rSR.0)