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/* i8080.c: Intel 8080/8085 CPU simulator
Copyright (c) 1997-2005, Charles E. Owen
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
CHARLES E. OWEN BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Except as contained in this notice, the name of Charles E. Owen shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from Charles E. Owen.
This software was modified by Bill Beech, Nov 2010, to allow emulation of Intel
iSBC Single Board Computers.
Copyright (c) 2011, William A. Beech
Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the "Software"),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:
The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
WILLIAM A. BEECH BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
Except as contained in this notice, the name of William A. Beech shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from William A. Beech.
cpu 8080 CPU
08 Oct 02 RMS Tied off spurious compiler warnings
23 Nov 10 WAB Modified for iSBC emulation
04 Dec 12 WAB Added 8080 interrupts
14 Dec 12 WAB Added 8085 interrupts
The register state for the 8080 CPU is:
A<0:7> Accumulator
BC<0:15> BC Register Pair
DE<0:15> DE Register Pair
HL<0:15> HL Register Pair
PSW<0:7> Program Status Word (Flags)
PC<0:15> Program counter
SP<0:15> Stack Pointer
The 8080 is an 8-bit CPU, which uses 16-bit registers to address
up to 64KB of memory.
The 78 basic instructions come in 1, 2, and 3-byte flavors.
This routine is the instruction decode routine for the 8080.
It is called from the simulator control program to execute
instructions in simulated memory, starting at the simulated PC.
It runs until 'reason' is set non-zero.
General notes:
1. Reasons to stop. The simulator can be stopped by:
HALT instruction
I/O error in I/O simulator
Invalid OP code (if ITRAP is set on CPU)
2. Interrupts.
There are 8 possible levels of interrupt, and in effect they
do a hardware CALL instruction to one of 8 possible low
memory addresses.
3. Non-existent memory. On the 8080, reads to non-existent memory
return 0FFh, and writes are ignored. In the simulator, the
largest possible memory is instantiated and initialized to zero.
Thus, only writes need be checked against actual memory size.
4. Adding I/O devices. These modules must be modified:
altair_cpu.c add I/O service routines to dev_table
altair_sys.c add pointer to data structures in sim_devices
?? ??? 11 - Original file.
16 Dec 12 - Modified to use isbc_80_10.cfg file to set base and size.
20 Dec 12 - Modified for basic interrupt function.
03 Mar 13 - Added trace function.
04 Mar 13 - Modified all instructions to truncate the affected register
at the end of the routine.
17 Mar 13 - Modified to enable/disable trace based on start and stop
addresses.
*/
#include "system_defs.h"
#define UNIT_V_OPSTOP (UNIT_V_UF) /* Stop on Invalid OP? */
#define UNIT_OPSTOP (1 << UNIT_V_OPSTOP)
#define UNIT_V_8085 (UNIT_V_UF+1) /* 8080/8085 switch */
#define UNIT_8085 (1 << UNIT_V_8085)
#define UNIT_V_TRACE (UNIT_V_UF+2) /* Trace switch */
#define UNIT_TRACE (1 << UNIT_V_TRACE)
/* Flag values to set proper positions in PSW */
#define CF 0x01
#define PF 0x04
#define AF 0x10
#define ZF 0x40
#define SF 0x80
/* Macros to handle the flags in the PSW
8080 has bit #1 always set. This is (not well) documented behavior. */
#define PSW_ALWAYS_ON (0x02) /* for 8080 */
#define PSW_MSK (CF|PF|AF|ZF|SF)
#define TOGGLE_FLAG(FLAG) (PSW ^= FLAG)
#define SET_FLAG(FLAG) (PSW |= FLAG)
#define CLR_FLAG(FLAG) (PSW &= ~FLAG)
#define GET_FLAG(FLAG) (PSW & FLAG)
#define COND_SET_FLAG(COND,FLAG) \
if (COND) SET_FLAG(FLAG); else CLR_FLAG(FLAG)
#define SET_XACK(VAL) (xack = VAL)
#define GET_XACK(FLAG) (xack &= FLAG)
/* values for IM bits */
#define ITRAP 0x100
#define SID 0x80
#define SOD 0x80
#define SDE 0x40
#define R75 0x10
#define IE 0x08
#define MSE 0x08
#define M75 0x04
#define M65 0x02
#define M55 0x01
/* register masks */
#define BYTE_R 0xFF
#define WORD_R 0xFFFF
/* storage for the rest of the registers */
uint32 PSW = 0; /* program status word */
uint32 A = 0; /* accumulator */
uint32 BC = 0; /* BC register pair */
uint32 DE = 0; /* DE register pair */
uint32 HL = 0; /* HL register pair */
uint32 SP = 0; /* Stack pointer */
uint32 saved_PC = 0; /* program counter */
uint32 IM = 0; /* Interrupt Mask Register */
uint32 xack = 0; /* XACK signal */
uint32 int_req = 0; /* Interrupt request */
int32 PCX; /* External view of PC */
int32 PC;
UNIT *uptr;
/* function prototypes */
void set_cpuint(int32 int_num);
void dumpregs(void);
int32 fetch_byte(int32 flag);
int32 fetch_word(void);
uint16 pop_word(void);
void push_word(uint16 val);
void setarith(int32 reg);
void setlogical(int32 reg);
void setinc(int32 reg);
int32 getreg(int32 reg);
void putreg(int32 reg, int32 val);
int32 getpair(int32 reg);
int32 getpush(int32 reg);
void putpush(int32 reg, int32 data);
void putpair(int32 reg, int32 val);
void parity(int32 reg);
int32 cond(int32 con);
t_stat i8080_ex (t_value *vptr, t_addr addr, UNIT *uptr, int32 sw);
t_stat i8080_dep (t_value val, t_addr addr, UNIT *uptr, int32 sw);
t_stat i8080_reset (DEVICE *dptr);
/* external function prototypes */
extern t_stat i8080_reset (DEVICE *dptr);
extern int32 get_mbyte(int32 addr);
extern int32 get_mword(int32 addr);
extern void put_mbyte(int32 addr, int32 val);
extern void put_mword(int32 addr, int32 val);
extern int32 sim_int_char;
extern uint32 sim_brk_types, sim_brk_dflt, sim_brk_summ; /* breakpoint info */
struct idev {
int32 (*routine)();
};
/* This is the I/O configuration table. There are 256 possible
device addresses, if a device is plugged to a port it's routine
address is here, 'nulldev' means no device is available
*/
extern struct idev dev_table[];
/* CPU data structures
i8080_dev CPU device descriptor
i8080_unit CPU unit descriptor
i8080_reg CPU register list
i8080_mod CPU modifiers list
*/
UNIT i8080_unit = { UDATA (NULL, 0, 65535) }; /* default 8080 */
REG i8080_reg[] = {
{ HRDATA (PC, saved_PC, 16) }, /* must be first for sim_PC */
{ HRDATA (PSW, PSW, 8) },
{ HRDATA (A, A, 8) },
{ HRDATA (BC, BC, 16) },
{ HRDATA (DE, DE, 16) },
{ HRDATA (HL, HL, 16) },
{ HRDATA (SP, SP, 16) },
{ HRDATA (IM, IM, 8) },
{ HRDATA (XACK, xack, 8) },
{ HRDATA (INTR, int_req, 32) },
{ HRDATA (WRU, sim_int_char, 8) },
{ NULL }
};
MTAB i8080_mod[] = {
{ UNIT_8085, 0, "8080", "8080", NULL },
{ UNIT_8085, UNIT_8085, "8085", "8085", NULL },
{ UNIT_OPSTOP, 0, "ITRAP", "ITRAP", NULL },
{ UNIT_OPSTOP, UNIT_OPSTOP, "NOITRAP", "NOITRAP", NULL },
{ UNIT_TRACE, 0, "NOTRACE", "NOTRACE", NULL },
{ UNIT_TRACE, UNIT_TRACE, "TRACE", "TRACE", NULL },
{ 0 }
};
DEBTAB i8080_debug[] = {
{ "ALL", DEBUG_all },
{ "FLOW", DEBUG_flow },
{ "READ", DEBUG_read },
{ "WRITE", DEBUG_write },
{ "LEV1", DEBUG_level1 },
{ "LEV2", DEBUG_level2 },
{ "REG", DEBUG_reg },
{ "ASM", DEBUG_asm },
{ NULL }
};
DEVICE i8080_dev = {
"CPU", //name
&i8080_unit, //units
i8080_reg, //registers
i8080_mod, //modifiers
1, //numunits
16, //aradix
16, //awidth
1, //aincr
16, //dradix
8, //dwidth
&i8080_ex, //examine
&i8080_dep, //deposit
// &i8080_reset, //reset
NULL, //reset
NULL, //boot
NULL, //attach
NULL, //detach
NULL, //ctxt
DEV_DEBUG, //flags
0, //dctrl
i8080_debug, //debflags
NULL, //msize
NULL //lname
};
/* tables for the disassembler */
char *opcode[] = {
"NOP", "LXI B,", "STAX B", "INX B", /* 0x00 */
"INR B", "DCR B", "MVI B,", "RLC",
"???", "DAD B", "LDAX B", "DCX B",
"INR C", "DCR C", "MVI C,", "RRC",
"???", "LXI D,", "STAX D", "INX D", /* 0x10 */
"INR D", "DCR D", "MVI D,", "RAL",
"???", "DAD D", "LDAX D", "DCX D",
"INR E", "DCR E", "MVI E,", "RAR",
"RIM", "LXI H,", "SHLD ", "INX H", /* 0x20 */
"INR H", "DCR H", "MVI H,", "DAA",
"???", "DAD H", "LHLD ", "DCX H",
"INR L", "DCR L", "MVI L", "CMA",
"SIM", "LXI SP,", "STA ", "INX SP", /* 0x30 */
"INR M", "DCR M", "MVI M,", "STC",
"???", "DAD SP", "LDA ", "DCX SP",
"INR A", "DCR A", "MVI A,", "CMC",
"MOV B,B", "MOV B,C", "MOV B,D", "MOV B,E", /* 0x40 */
"MOV B,H", "MOV B,L", "MOV B,M", "MOV B,A",
"MOV C,B", "MOV C,C", "MOV C,D", "MOV C,E",
"MOV C,H", "MOV C,L", "MOV C,M", "MOV C,A",
"MOV D,B", "MOV D,C", "MOV D,D", "MOV D,E", /* 0x50 */
"MOV D,H", "MOV D,L", "MOV D,M", "MOV D,A",
"MOV E,B", "MOV E,C", "MOV E,D", "MOV E,E",
"MOV E,H", "MOV E,L", "MOV E,M", "MOV E,A",
"MOV H,B", "MOV H,C", "MOV H,D", "MOV H,E", /* 0x60 */
"MOV H,H", "MOV H,L", "MOV H,M", "MOV H,A",
"MOV L,B", "MOV L,C", "MOV L,D", "MOV L,E",
"MOV L,H", "MOV L,L", "MOV L,M", "MOV L,A",
"MOV M,B", "MOV M,C", "MOV M,D", "MOV M,E", /* 0x70 */
"MOV M,H", "MOV M,L", "HLT", "MOV M,A",
"MOV A,B", "MOV A,C", "MOV A,D", "MOV A,E",
"MOV A,H", "MOV A,L", "MOV A,M", "MOV A,A",
"ADD B", "ADD C", "ADD D", "ADD E", /* 0x80 */
"ADD H", "ADD L", "ADD M", "ADD A",
"ADC B", "ADC C", "ADC D", "ADC E",
"ADC H", "ADC L", "ADC M", "ADC A",
"SUB B", "SUB C", "SUB D", "SUB E", /* 0x90 */
"SUB H", "SUB L", "SUB M", "SUB A",
"SBB B", "SBB C", "SBB D", "SBB E",
"SBB H", "SBB L", "SBB M", "SBB A",
"ANA B", "ANA C", "ANA D", "ANA E", /* 0xA0 */
"ANA H", "ANA L", "ANA M", "ANA A",
"XRA B", "XRA C", "XRA D", "XRA E",
"XRA H", "XRA L", "XRA M", "XRA A",
"ORA B", "ORA C", "ORA D", "ORA E", /* 0xB0 */
"ORA H", "ORA L", "ORA M", "ORA A",
"CMP B", "CMP C", "CMP D", "CMP E",
"CMP H", "CMP L", "CMP M", "CMP A",
"RNZ", "POP B", "JNZ ", "JMP ", /* 0xC0 */
"CNZ ", "PUSH B", "ADI ", "RST 0",
"RZ", "RET", "JZ ", "???",
"CZ ", "CALL ", "ACI ", "RST 1",
"RNC", "POP D", "JNC ", "OUT ", /* 0xD0 */
"CNC ", "PUSH D", "SUI ", "RST 2",
"RC", "???", "JC ", "IN ",
"CC ", "???", "SBI ", "RST 3",
"RPO", "POP H", "JPO ", "XTHL", /* 0xE0 */
"CPO ", "PUSH H", "ANI ", "RST 4",
"RPE", "PCHL", "JPE ", "XCHG",
"CPE ", "???", "XRI ", "RST 5",
"RP", "POP PSW", "JP ", "DI", /* 0xF0 */
"CP ", "PUSH PSW", "ORI ", "RST 6",
"RM", "SPHL", "JM ", "EI",
"CM ", "???", "CPI ", "RST 7",
};
int32 oplen[256] = {
1,3,1,1,1,1,2,1,0,1,1,1,1,1,2,1,
0,3,1,1,1,1,2,1,0,1,1,1,1,1,2,1,
1,3,3,1,1,1,2,1,0,1,3,1,1,1,2,1,
1,3,3,1,1,1,2,1,0,1,3,1,1,1,2,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,
1,1,3,3,3,1,2,1,1,1,3,0,3,3,2,1,
1,1,3,2,3,1,2,1,1,0,3,2,3,0,2,1,
1,1,3,1,3,1,2,1,1,1,3,1,3,0,2,1,
1,1,3,1,3,1,2,1,1,1,3,1,3,0,2,1 };
void set_cpuint(int32 int_num)
{
int_req |= int_num;
}
//FILE *fpd;
/* instruction simulator */
int32 sim_instr (void)
{
extern int32 sim_interval;
uint32 IR, OP, DAR, reason, adr;
PC = saved_PC & WORD_R; /* load local PC */
reason = 0;
uptr = i8080_dev.units;
if (i8080_dev.dctrl & DEBUG_flow) {
if (uptr->flags & UNIT_8085)
sim_printf("CPU = 8085\n");
else
sim_printf("CPU = 8080\n");
}
/* Main instruction fetch/decode loop */
while (reason == 0) { /* loop until halted */
// if (PC == 0x1000) { /* turn on debugging */
// i8080_dev.dctrl = DEBUG_asm + DEBUG_reg;
// reason = STOP_HALT;
// }
if (i8080_dev.dctrl & DEBUG_reg) {
dumpregs();
sim_printf("\n");
}
if (sim_interval <= 0) { /* check clock queue */
if ((reason = sim_process_event()))
break;
}
sim_interval--; /* countdown clock */
if (int_req > 0) { /* interrupt? */
// sim_printf("\ni8080: int_req=%04X IM=%04X", int_req, IM);
if (uptr->flags & UNIT_8085) { /* 8085 */
if (int_req & ITRAP) { /* int */
push_word(PC);
PC = 0x0024;
int_req &= ~ITRAP;
} else if (IM & IE) {
if (int_req & I75 && IM & M75) { /* int 7.5 */
push_word(PC);
PC = 0x003C;
int_req &= ~I75;
} else if (int_req & I65 && IM & M65) { /* int 6.5 */
push_word(PC);
PC = 0x0034;
int_req &= ~I65;
} else if (int_req & I55 && IM & M55) { /* int 5.5 */
push_word(PC);
PC = 0x002C;
int_req &= ~I55;
} else if (int_req & INT_R) { /* intr */
push_word(PC); /* do an RST 7 */
PC = 0x0038;
int_req &= ~INT_R;
}
}
} else { /* 8080 */
if (IM & IE) { /* enabled? */
push_word(PC); /* do an RST 7 */
PC = 0x0038;
int_req &= ~INT_R;
// sim_printf("\ni8080: int_req=%04X", int_req);
}
}
} /* end interrupt */
if (sim_brk_summ &&
sim_brk_test (PC, SWMASK ('E'))) { /* breakpoint? */
reason = STOP_IBKPT; /* stop simulation */
break;
}
PCX = PC;
// fprintf(fpd, "%04X\n", PC);
// fflush(fpd);
if (uptr->flags & UNIT_TRACE) {
dumpregs();
sim_printf("\n");
}
IR = OP = fetch_byte(0); /* instruction fetch */
if (GET_XACK(1) == 0) { /* no XACK for instruction fetch */
reason = STOP_XACK;
sim_printf("Stopped for XACK-1 PC=%04X\n", --PC);
continue;
}
if (OP == 0x76) { /* HLT Instruction*/
reason = STOP_HALT;
PC--;
continue;
}
/* Handle below all operations which refer to registers or
register pairs. After that, a large switch statement
takes care of all other opcodes */
if ((OP & 0xC0) == 0x40) { /* MOV */
DAR = getreg(OP & 0x07);
putreg((OP >> 3) & 0x07, DAR);
goto loop_end;
}
if ((OP & 0xC7) == 0x06) { /* MVI */
putreg((OP >> 3) & 0x07, fetch_byte(1));
goto loop_end;
}
if ((OP & 0xCF) == 0x01) { /* LXI */
DAR = fetch_word();
putpair((OP >> 4) & 0x03, DAR);
goto loop_end;
}
if ((OP & 0xEF) == 0x0A) { /* LDAX */
DAR = getpair((OP >> 4) & 0x03);
putreg(7, get_mbyte(DAR));
goto loop_end;
}
if ((OP & 0xEF) == 0x02) { /* STAX */
DAR = getpair((OP >> 4) & 0x03);
put_mbyte(DAR, getreg(7));
goto loop_end;
}
if ((OP & 0xF8) == 0xB8) { /* CMP */
DAR = A & 0xFF;
DAR -= getreg(OP & 0x07);
setarith(DAR);
DAR &= BYTE_R;
goto loop_end;
}
if ((OP & 0xC7) == 0xC2) { /* JMP <condition> */
adr = fetch_word();
if (cond((OP >> 3) & 0x07))
PC = adr;
goto loop_end;
}
if ((OP & 0xC7) == 0xC4) { /* CALL <condition> */
adr = fetch_word();
if (cond((OP >> 3) & 0x07)) {
push_word(PC);
PC = adr;
}
goto loop_end;
}
if ((OP & 0xC7) == 0xC0) { /* RET <condition> */
if (cond((OP >> 3) & 0x07)) {
PC = pop_word();
}
goto loop_end;
}
if ((OP & 0xC7) == 0xC7) { /* RST */
push_word(PC);
PC = OP & 0x38;
goto loop_end;
}
if ((OP & 0xCF) == 0xC5) { /* PUSH */
DAR = getpush((OP >> 4) & 0x03);
push_word(DAR);
goto loop_end;
}
if ((OP & 0xCF) == 0xC1) { /* POP */
DAR = pop_word();
putpush((OP >> 4) & 0x03, DAR);
goto loop_end;
}
if ((OP & 0xF8) == 0x80) { /* ADD */
A += getreg(OP & 0x07);
setarith(A);
A &= BYTE_R;
goto loop_end;
}
if ((OP & 0xF8) == 0x88) { /* ADC */
A += getreg(OP & 0x07);
if (GET_FLAG(CF))
A++;
setarith(A);
A &= BYTE_R;
goto loop_end;
}
if ((OP & 0xF8) == 0x90) { /* SUB */
A -= getreg(OP & 0x07);
setarith(A);
A &= BYTE_R;
goto loop_end;
}
if ((OP & 0xF8) == 0x98) { /* SBB */
A -= getreg(OP & 0x07);
if (GET_FLAG(CF))
A--;
setarith(A);
A &= BYTE_R;
goto loop_end;
}
if ((OP & 0xC7) == 0x04) { /* INR */
DAR = getreg((OP >> 3) & 0x07);
DAR++;
setinc(DAR);
// DAR &= BYTE_R;
putreg((OP >> 3) & 0x07, DAR);
goto loop_end;
}
if ((OP & 0xC7) == 0x05) { /* DCR */
DAR = getreg((OP >> 3) & 0x07);
DAR--;
setinc(DAR);
// DAR &= BYTE_R;
putreg((OP >> 3) & 0x07, DAR);
goto loop_end;
}
if ((OP & 0xCF) == 0x03) { /* INX */
DAR = getpair((OP >> 4) & 0x03);
DAR++;
// DAR &= WORD_R;
putpair((OP >> 4) & 0x03, DAR);
goto loop_end;
}
if ((OP & 0xCF) == 0x0B) { /* DCX */
DAR = getpair((OP >> 4) & 0x03);
DAR--;
// DAR &= WORD_R;
putpair((OP >> 4) & 0x03, DAR);
goto loop_end;
}
if ((OP & 0xCF) == 0x09) { /* DAD */
HL += getpair((OP >> 4) & 0x03);
COND_SET_FLAG(HL & 0x10000, CF);
HL &= WORD_R;
goto loop_end;
}
if ((OP & 0xF8) == 0xA0) { /* ANA */
A &= getreg(OP & 0x07);
setlogical(A);
goto loop_end;
}
if ((OP & 0xF8) == 0xA8) { /* XRA */
A ^= getreg(OP & 0x07);
setlogical(A);
A &= BYTE_R;
goto loop_end;
}
if ((OP & 0xF8) == 0xB0) { /* ORA */
A |= getreg(OP & 0x07);
setlogical(A);
goto loop_end;
}
/* The Big Instruction Decode Switch */
switch (IR) {
/* 8085 instructions only */
case 0x20: /* RIM */
if (i8080_unit.flags & UNIT_8085) { /* 8085 */
A = IM;
} else { /* 8080 */
reason = STOP_OPCODE;
PC--;
}
break;
case 0x30: /* SIM */
if (i8080_unit.flags & UNIT_8085) { /* 8085 */
if (A & MSE) {
IM &= 0xF8;
IM |= A & 0x07;
}
if (A & I75) { /* reset RST 7.5 FF */
}
} else { /* 8080 */
reason = STOP_OPCODE;
PC--;
}
break;
/* Logical instructions */
case 0xFE: /* CPI */
DAR = A;
DAR -= fetch_byte(1);
// DAR &= BYTE_R;
setarith(DAR);
break;
case 0xE6: /* ANI */
A &= fetch_byte(1);
setlogical(A);
break;
case 0xEE: /* XRI */
A ^= fetch_byte(1);
// DAR &= BYTE_R;
setlogical(A);
break;
case 0xF6: /* ORI */
A |= fetch_byte(1);
setlogical(A);
break;
/* Jump instructions */
case 0xC3: /* JMP */
PC = fetch_word();
break;
case 0xE9: /* PCHL */
PC = HL;
break;
case 0xCD: /* CALL */
adr = fetch_word();
push_word(PC);
PC = adr;
break;
case 0xC9: /* RET */
PC = pop_word();
break;
/* Data Transfer Group */
case 0x32: /* STA */
DAR = fetch_word();
DAR &= WORD_R;
put_mbyte(DAR, A);
break;
case 0x3A: /* LDA */
DAR = fetch_word();
DAR &= WORD_R;
A = get_mbyte(DAR);
break;
case 0x22: /* SHLD */
DAR = fetch_word();
DAR &= WORD_R;
put_mword(DAR, HL);
break;
case 0x2A: /* LHLD */
DAR = fetch_word();
DAR &= WORD_R;
HL = get_mword(DAR);
break;
case 0xEB: /* XCHG */
DAR = HL;
HL = DE;
HL &= WORD_R;
DE = DAR;
DE &= WORD_R;
break;
/* Arithmetic Group */
case 0xC6: /* ADI */
A += fetch_byte(1);
setarith(A);
A &= BYTE_R;
break;
case 0xCE: /* ACI */
A += fetch_byte(1);
if (GET_FLAG(CF))
A++;
setarith(A);
A &= BYTE_R;
break;
case 0xD6: /* SUI */
A -= fetch_byte(1);
setarith(A);
A &= BYTE_R;
break;
case 0xDE: /* SBI */
A -= fetch_byte(1);
if (GET_FLAG(CF))
A--;
setarith(A);
A &= BYTE_R;
break;
case 0x27: /* DAA */
DAR = A & 0x0F;
if (DAR > 9 || GET_FLAG(AF)) {
DAR += 6;
A &= 0xF0;
A |= DAR & 0x0F;
COND_SET_FLAG(DAR & 0x10, AF);
}
DAR = (A >> 4) & 0x0F;
if (DAR > 9 || GET_FLAG(AF)) {
DAR += 6;
if (GET_FLAG(AF)) DAR++;
A &= 0x0F;
A |= (DAR << 4);
}
COND_SET_FLAG(DAR & 0x10, CF);
COND_SET_FLAG(A & 0x80, SF);
COND_SET_FLAG((A & 0xFF) == 0, ZF);
parity(A);
break;
case 0x07: /* RLC */
COND_SET_FLAG(A & 0x80, CF);
A = (A << 1) & 0xFF;
if (GET_FLAG(CF))
A |= 0x01;
A &= BYTE_R;
break;
case 0x0F: /* RRC */
COND_SET_FLAG(A & 0x01, CF);
A = (A >> 1) & 0xFF;
if (GET_FLAG(CF))
A |= 0x80;
A &= BYTE_R;
break;
case 0x17: /* RAL */
DAR = GET_FLAG(CF);
COND_SET_FLAG(A & 0x80, CF);
A = (A << 1) & 0xFF;
if (DAR)
A |= 0x01;
A &= BYTE_R;
break;
case 0x1F: /* RAR */
DAR = GET_FLAG(CF);
COND_SET_FLAG(A & 0x01, CF);
A = (A >> 1) & 0xFF;
if (DAR)
A |= 0x80;
A &= BYTE_R;
break;
case 0x2F: /* CMA */
A = ~A;
A &= BYTE_R;
break;
case 0x3F: /* CMC */
TOGGLE_FLAG(CF);
break;
case 0x37: /* STC */
SET_FLAG(CF);
break;
/* Stack, I/O & Machine Control Group */
case 0x00: /* NOP */
break;
case 0xE3: /* XTHL */
DAR = pop_word();
push_word(HL);
HL = DAR;
HL &= WORD_R;
break;
case 0xF9: /* SPHL */
SP = HL;
break;
case 0xFB: /* EI */
IM |= IE;
// sim_printf("\nEI: pc=%04X", PC - 1);
break;
case 0xF3: /* DI */
IM &= ~IE;
// sim_printf("\nDI: pc=%04X", PC - 1);
break;
case 0xDB: /* IN */
DAR = fetch_byte(1);
A = dev_table[DAR].routine(0, 0);
A &= BYTE_R;
break;
case 0xD3: /* OUT */
DAR = fetch_byte(1);
dev_table[DAR].routine(1, A);
break;
default: /* undefined opcode */
if (i8080_unit.flags & UNIT_OPSTOP) {
reason = STOP_OPCODE;
PC--;
}
break;
}
loop_end:
if (GET_XACK(1) == 0) { /* no XACK for instruction fetch */
reason = STOP_XACK;
sim_printf("Stopped for XACK-2 PC=%04X\n", --PC);
continue;
}
}
/* Simulation halted */
saved_PC = PC;
// fclose(fpd);
return reason;
}
/* dump the registers */
void dumpregs(void)
{
sim_printf(" A=%02X BC=%04X DE=%04X HL=%04X SP=%04X IM=%02X XACK=%d\n",
A, BC, DE, HL, SP, IM, xack);
sim_printf(" CF=%d ZF=%d AF=%d SF=%d PF=%d\n",
GET_FLAG(CF) ? 1 : 0,
GET_FLAG(ZF) ? 1 : 0,
GET_FLAG(AF) ? 1 : 0,
GET_FLAG(SF) ? 1 : 0,
GET_FLAG(PF) ? 1 : 0);
}
/* fetch an instruction or byte */
int32 fetch_byte(int32 flag)
{
uint32 val;
val = get_mbyte(PC) & 0xFF; /* fetch byte */
if (i8080_dev.dctrl & DEBUG_asm || uptr->flags & UNIT_TRACE) { /* display source code */
switch (flag) {
case 0: /* opcode fetch */
sim_printf("OP=%02X %04X %s", val, PC, opcode[val]);
break;
case 1: /* byte operand fetch */
sim_printf("0%02XH", val);
break;
}
}
PC = (PC + 1) & ADDRMASK; /* increment PC */
val &= BYTE_R;
return val;
}
/* fetch a word */
int32 fetch_word(void)
{
uint16 val;
val = get_mbyte(PC) & BYTE_R; /* fetch low byte */
val |= get_mbyte(PC + 1) << 8; /* fetch high byte */
if (i8080_dev.dctrl & DEBUG_asm || uptr->flags & UNIT_TRACE) /* display source code */
sim_printf("0%04XH", val);
PC = (PC + 2) & ADDRMASK; /* increment PC */
val &= WORD_R;
return val;
}
/* push a word to the stack */
void push_word(uint16 val)
{
SP--;
put_mbyte(SP, (val >> 8));
SP--;
put_mbyte(SP, val & 0xFF);
}
/* pop a word from the stack */
uint16 pop_word(void)
{
register uint16 res;
res = get_mbyte(SP);
SP++;
res |= get_mbyte(SP) << 8;
SP++;
return res;
}
/* Test an 8080 flag condition and return 1 if true, 0 if false */
int32 cond(int32 con)
{
switch (con) {
case 0: /* NZ */
if (GET_FLAG(ZF) == 0) return 1;
break;
case 1: /* Z */
if (GET_FLAG(ZF)) return 1;
break;
case 2: /* NC */
if (GET_FLAG(CF) == 0) return 1;
break;
case 3: /* C */
if (GET_FLAG(CF)) return 1;
break;
case 4: /* PO */
if (GET_FLAG(PF) == 0) return 1;
break;
case 5: /* PE */
if (GET_FLAG(PF)) return 1;
break;
case 6: /* P */
if (GET_FLAG(SF) == 0) return 1;
break;
case 7: /* M */
if (GET_FLAG(SF)) return 1;
break;
default:
break;
}
return 0;
}
/* Set the <C>arry, <S>ign, <Z>ero and <P>arity flags following
an arithmetic operation on 'reg'.
*/
void setarith(int32 reg)
{
COND_SET_FLAG(reg & 0x100, CF);
COND_SET_FLAG(reg & 0x80, SF);
COND_SET_FLAG((reg & BYTE_R) == 0, ZF);
CLR_FLAG(AF);
parity(reg);
}
/* Set the <C>arry, <S>ign, <Z>ero amd <P>arity flags following
a logical (bitwise) operation on 'reg'.
*/
void setlogical(int32 reg)
{
CLR_FLAG(CF);
COND_SET_FLAG(reg & 0x80, SF);
COND_SET_FLAG((reg & BYTE_R) == 0, ZF);
CLR_FLAG(AF);
parity(reg);
}
/* Set the Parity (P) flag based on parity of 'reg', i.e., number
of bits on even: P=0200000, else P=0
*/
void parity(int32 reg)
{
int32 bc = 0;
if (reg & 0x01) bc++;
if (reg & 0x02) bc++;
if (reg & 0x04) bc++;
if (reg & 0x08) bc++;
if (reg & 0x10) bc++;
if (reg & 0x20) bc++;
if (reg & 0x40) bc++;
if (reg & 0x80) bc++;
if (bc & 0x01)
CLR_FLAG(PF);
else
SET_FLAG(PF);
}
/* Set the <S>ign, <Z>ero amd <P>arity flags following
an INR/DCR operation on 'reg'.
*/
void setinc(int32 reg)
{
COND_SET_FLAG(reg & 0x80, SF);
COND_SET_FLAG((reg & BYTE_R) == 0, ZF);
parity(reg);
}
/* Get an 8080 register and return it */
int32 getreg(int32 reg)
{
switch (reg) {
case 0: /* reg B */
// sim_printf("reg=%04X BC=%04X ret=%04X\n",
// reg, BC, (BC >>8) & 0xff);
return ((BC >>8) & BYTE_R);
case 1: /* reg C */
return (BC & BYTE_R);
case 2: /* reg D */
return ((DE >>8) & BYTE_R);
case 3: /* reg E */
return (DE & BYTE_R);
case 4: /* reg H */
return ((HL >>8) & BYTE_R);
case 5: /* reg L */
return (HL & BYTE_R);
case 6: /* reg M */
return (get_mbyte(HL));
case 7: /* reg A */
return (A);
default:
break;
}
return 0;
}
/* Put a value into an 8-bit 8080 register from memory */
void putreg(int32 reg, int32 val)
{
switch (reg) {
case 0: /* reg B */
// sim_printf("reg=%04X val=%04X\n", reg, val);
BC = BC & BYTE_R;
// sim_printf("BC&0x00ff=%04X val<<8=%04X\n", BC, val<<8);
BC = BC | (val <<8);
break;
case 1: /* reg C */
BC = BC & 0xFF00;
BC = BC | val;
break;
case 2: /* reg D */
DE = DE & BYTE_R;
DE = DE | (val <<8);
break;
case 3: /* reg E */
DE = DE & 0xFF00;
DE = DE | val;
break;
case 4: /* reg H */
HL = HL & BYTE_R;
HL = HL | (val <<8);
break;
case 5: /* reg L */
HL = HL & 0xFF00;
HL = HL | val;
break;
case 6: /* reg M */
put_mbyte(HL, val);
break;
case 7: /* reg A */
A = val & BYTE_R;
default:
break;
}
}
/* Return the value of a selected register pair */
int32 getpair(int32 reg)
{
switch (reg) {
case 0: /* reg BC */
return (BC);
case 1: /* reg DE */
return (DE);
case 2: /* reg HL */
return (HL);
case 3: /* reg SP */
return (SP);
default:
break;
}
return 0;
}
/* Return the value of a selected register pair, in PUSH
format where 3 means A & flags, not SP */
int32 getpush(int32 reg)
{
int32 stat;
switch (reg) {
case 0: /* reg BC */
return (BC);
case 1: /* reg DE */
return (DE);
case 2: /* reg HL */
return (HL);
case 3: /* reg (A << 8) | PSW */
stat = A << 8 | PSW;
return (stat);
default:
break;
}
return 0;
}
/* Place data into the indicated register pair, in PUSH
format where 3 means A& flags, not SP */
void putpush(int32 reg, int32 data)
{
switch (reg) {
case 0: /* reg BC */
BC = data;
break;
case 1: /* reg DE */
DE = data;
break;
case 2: /* reg HL */
HL = data;
break;
case 3: /* reg (A << 8) | PSW */
A = (data >> 8) & BYTE_R;
PSW = data & BYTE_R;
break;
default:
break;
}
}
/* Put a value into an 8080 register pair */
void putpair(int32 reg, int32 val)
{
switch (reg) {
case 0: /* reg BC */
BC = val;
break;
case 1: /* reg DE */
DE = val;
break;
case 2: /* reg HL */
HL = val;
break;
case 3: /* reg SP */
SP = val;
break;
default:
break;
}
}
/* Reset routine */
t_stat i8080_reset (DEVICE *dptr)
{
PSW = PSW_ALWAYS_ON;
CLR_FLAG(CF);
CLR_FLAG(ZF);
saved_PC = 0;
int_req = 0;
IM = 0;
sim_brk_types = sim_brk_dflt = SWMASK ('E');
sim_printf(" 8080: Reset\n");
// fpd = fopen("trace.txt", "w");
return SCPE_OK;
}
/* Memory examine */
t_stat i8080_ex (t_value *vptr, t_addr addr, UNIT *uptr, int32 sw)
{
if (addr >= MEMSIZE)
return SCPE_NXM;
if (vptr != NULL)
*vptr = get_mbyte(addr);
return SCPE_OK;
}
/* Memory deposit */
t_stat i8080_dep (t_value val, t_addr addr, UNIT *uptr, int32 sw)
{
if (addr >= MEMSIZE)
return SCPE_NXM;
put_mbyte(addr, val);
return SCPE_OK;
}
/* This is the binary loader. The input file is considered to be
a string of literal bytes with no special format. The load
starts at the current value of the PC.
*/
int32 sim_load (FILE *fileref, char *cptr, char *fnam, int flag)
{
int32 i, addr = 0, cnt = 0;
if ((*cptr != 0) || (flag != 0)) return SCPE_ARG;
addr = saved_PC;
while ((i = getc (fileref)) != EOF) {
put_mbyte(addr, i);
addr++;
cnt++;
} /* end while */
sim_printf ("%d Bytes loaded.\n", cnt);
return (SCPE_OK);
}
/* Symbolic output
Inputs:
*of = output stream
addr = current PC
*val = pointer to values
*uptr = pointer to unit
sw = switches
Outputs:
status = error code
*/
t_stat fprint_sym (FILE *of, t_addr addr, t_value *val,
UNIT *uptr, int32 sw)
{
int32 cflag, c1, c2, inst, adr;
cflag = (uptr == NULL) || (uptr == &i8080_unit);
c1 = (val[0] >> 8) & 0x7F;
c2 = val[0] & 0x7F;
if (sw & SWMASK ('A')) {
fprintf (of, (c2 < 0x20)? "<%02X>": "%c", c2);
return SCPE_OK;
}
if (sw & SWMASK ('C')) {
fprintf (of, (c1 < 0x20)? "<%02X>": "%c", c1);
fprintf (of, (c2 < 0x20)? "<%02X>": "%c", c2);
return SCPE_OK;
}
if (!(sw & SWMASK ('M'))) return SCPE_ARG;
inst = val[0];
fprintf (of, "%s", opcode[inst]);
if (oplen[inst] == 2) {
if (strchr(opcode[inst], ' ') != NULL)
fprintf (of, ",");
else fprintf (of, " ");
fprintf (of, "%02X", val[1]);
}
if (oplen[inst] == 3) {
adr = val[1] & 0xFF;
adr |= (val[2] << 8) & 0xff00;
if (strchr(opcode[inst], ' ') != NULL)
fprintf (of, ",");
else fprintf (of, " ");
fprintf (of, "%04X", adr);
}
return -(oplen[inst] - 1);
}
/* Symbolic input
Inputs:
*cptr = pointer to input string
addr = current PC
*uptr = pointer to unit
*val = pointer to output values
sw = switches
Outputs:
status = error status
*/
t_stat parse_sym (char *cptr, t_addr addr, UNIT *uptr, t_value *val, int32 sw)
{
int32 cflag, i = 0, j, r;
char gbuf[CBUFSIZE];
cflag = (uptr == NULL) || (uptr == &i8080_unit);
while (isspace (*cptr)) cptr++; /* absorb spaces */
if ((sw & SWMASK ('A')) || ((*cptr == '\'') && cptr++)) { /* ASCII char? */
if (cptr[0] == 0) return SCPE_ARG; /* must have 1 char */
val[0] = (uint32) cptr[0];
return SCPE_OK;
}
if ((sw & SWMASK ('C')) || ((*cptr == '"') && cptr++)) { /* ASCII string? */
if (cptr[0] == 0) return SCPE_ARG; /* must have 1 char */
val[0] = ((uint32) cptr[0] << 8) + (uint32) cptr[1];
return SCPE_OK;
}
/* An instruction: get opcode (all characters until null, comma,
or numeric (including spaces).
*/
while (1) {
if (*cptr == ',' || *cptr == '\0' ||
isdigit(*cptr))
break;
gbuf[i] = toupper(*cptr);
cptr++;
i++;
}
/* Allow for RST which has numeric as part of opcode */
if (toupper(gbuf[0]) == 'R' &&
toupper(gbuf[1]) == 'S' &&
toupper(gbuf[2]) == 'T') {
gbuf[i] = toupper(*cptr);
cptr++;
i++;
}
/* Allow for 'MOV' which is only opcode that has comma in it. */
if (toupper(gbuf[0]) == 'M' &&
toupper(gbuf[1]) == 'O' &&
toupper(gbuf[2]) == 'V') {
gbuf[i] = toupper(*cptr);
cptr++;
i++;
gbuf[i] = toupper(*cptr);
cptr++;
i++;
}
/* kill trailing spaces if any */
gbuf[i] = '\0';
for (j = i - 1; gbuf[j] == ' '; j--) {
gbuf[j] = '\0';
}
/* find opcode in table */
for (j = 0; j < 256; j++) {
if (strcmp(gbuf, opcode[j]) == 0)
break;
}
if (j > 255) /* not found */
return SCPE_ARG;
val[0] = j; /* store opcode */
if (oplen[j] < 2) /* if 1-byter we are done */
return SCPE_OK;
if (*cptr == ',') cptr++;
cptr = get_glyph(cptr, gbuf, 0); /* get address */
sscanf(gbuf, "%o", &r);
if (oplen[j] == 2) {
val[1] = r & 0xFF;
return (-1);
}
val[1] = r & 0xFF;
val[2] = (r >> 8) & 0xFF;
return (-2);
}
/* end of i8080.c */