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- /*
- * rarely used EEPROM code
- * (C) notaz, 2007-2009
- *
- * This work is licensed under the terms of MAME license.
- * See COPYING file in the top-level directory.
- *
- * (see Genesis Plus for Wii/GC code and docs for info,
- * full game list and better code).
- */
- #include "pico_int.h"
- static unsigned int last_write = 0xffff0000;
- // eeprom_status: LA.. s.la (L=pending SCL, A=pending SDA,
- // s=started, l=old SCL, a=old SDA)
- static void EEPROM_write_do(unsigned int d) // ???? ??la (l=SCL, a=SDA)
- {
- unsigned int sreg = Pico.m.eeprom_status, saddr = Pico.m.eeprom_addr;
- unsigned int scyc = Pico.m.eeprom_cycle, ssa = Pico.m.eeprom_slave;
- elprintf(EL_EEPROM, "eeprom: scl/sda: %i/%i -> %i/%i, newtime=%i", (sreg&2)>>1, sreg&1,
- (d&2)>>1, d&1, SekCyclesDone() - last_write);
- saddr &= 0x1fff;
- if(sreg & d & 2) {
- // SCL was and is still high..
- if((sreg & 1) && !(d&1)) {
- // ..and SDA went low, means it's a start command, so clear internal addr reg and clock counter
- elprintf(EL_EEPROM, "eeprom: -start-");
- //saddr = 0;
- scyc = 0;
- sreg |= 8;
- } else if(!(sreg & 1) && (d&1)) {
- // SDA went high == stop command
- elprintf(EL_EEPROM, "eeprom: -stop-");
- sreg &= ~8;
- }
- }
- else if((sreg & 8) && !(sreg & 2) && (d&2))
- {
- // we are started and SCL went high - next cycle
- scyc++; // pre-increment
- if(Pico.sv.eeprom_type) {
- // X24C02+
- if((ssa&1) && scyc == 18) {
- scyc = 9;
- saddr++; // next address in read mode
- /*if(Pico.sv.eeprom_type==2) saddr&=0xff; else*/ saddr&=0x1fff; // mask
- }
- else if(Pico.sv.eeprom_type == 2 && scyc == 27) scyc = 18;
- else if(scyc == 36) scyc = 27;
- } else {
- // X24C01
- if(scyc == 18) {
- scyc = 9; // wrap
- if(saddr&1) { saddr+=2; saddr&=0xff; } // next addr in read mode
- }
- }
- elprintf(EL_EEPROM, "eeprom: scyc: %i", scyc);
- }
- else if((sreg & 8) && (sreg & 2) && !(d&2))
- {
- // we are started and SCL went low (falling edge)
- if(Pico.sv.eeprom_type) {
- // X24C02+
- if(scyc == 9 || scyc == 18 || scyc == 27); // ACK cycles
- else if( (Pico.sv.eeprom_type == 3 && scyc > 27) || (Pico.sv.eeprom_type == 2 && scyc > 18) ) {
- if(!(ssa&1)) {
- // data write
- unsigned char *pm=Pico.sv.data+saddr;
- *pm <<= 1; *pm |= d&1;
- if(scyc == 26 || scyc == 35) {
- saddr=(saddr&~0xf)|((saddr+1)&0xf); // only 4 (?) lowest bits are incremented
- elprintf(EL_EEPROM, "eeprom: write done, addr inc to: %x, last byte=%02x", saddr, *pm);
- }
- Pico.sv.changed = 1;
- }
- } else if(scyc > 9) {
- if(!(ssa&1)) {
- // we latch another addr bit
- saddr<<=1;
- if(Pico.sv.eeprom_type == 2) saddr&=0xff; else saddr&=0x1fff; // mask
- saddr|=d&1;
- if(scyc==17||scyc==26) {
- elprintf(EL_EEPROM, "eeprom: addr reg done: %x", saddr);
- if(scyc==17&&Pico.sv.eeprom_type==2) { saddr&=0xff; saddr|=(ssa<<7)&0x700; } // add device bits too
- }
- }
- } else {
- // slave address
- ssa<<=1; ssa|=d&1;
- if(scyc==8) elprintf(EL_EEPROM, "eeprom: slave done: %x", ssa);
- }
- } else {
- // X24C01
- if(scyc == 9); // ACK cycle, do nothing
- else if(scyc > 9) {
- if(!(saddr&1)) {
- // data write
- unsigned char *pm=Pico.sv.data+(saddr>>1);
- *pm <<= 1; *pm |= d&1;
- if(scyc == 17) {
- saddr=(saddr&0xf9)|((saddr+2)&6); // only 2 lowest bits are incremented
- elprintf(EL_EEPROM, "eeprom: write done, addr inc to: %x, last byte=%02x", saddr>>1, *pm);
- }
- Pico.sv.changed = 1;
- }
- } else {
- // we latch another addr bit
- saddr<<=1; saddr|=d&1; saddr&=0xff;
- if(scyc==8) elprintf(EL_EEPROM, "eeprom: addr done: %x", saddr>>1);
- }
- }
- }
- sreg &= ~3; sreg |= d&3; // remember SCL and SDA
- Pico.m.eeprom_status = (unsigned char) sreg;
- Pico.m.eeprom_cycle = (unsigned char) scyc;
- Pico.m.eeprom_slave = (unsigned char) ssa;
- Pico.m.eeprom_addr = (unsigned short)saddr;
- }
- static void EEPROM_upd_pending(unsigned int d)
- {
- unsigned int d1, sreg = Pico.m.eeprom_status;
- sreg &= ~0xc0;
- // SCL
- d1 = (d >> Pico.sv.eeprom_bit_cl) & 1;
- sreg |= d1 << 7;
- // SDA in
- d1 = (d >> Pico.sv.eeprom_bit_in) & 1;
- sreg |= d1 << 6;
- Pico.m.eeprom_status = (unsigned char) sreg;
- }
- void EEPROM_write16(unsigned int d)
- {
- // this diff must be at most 16 for NBA Jam to work
- if (SekCyclesDone() - last_write < 16) {
- // just update pending state
- elprintf(EL_EEPROM, "eeprom: skip because cycles=%i",
- SekCyclesDone() - last_write);
- EEPROM_upd_pending(d);
- } else {
- int srs = Pico.m.eeprom_status;
- EEPROM_write_do(srs >> 6); // execute pending
- EEPROM_upd_pending(d);
- if ((srs ^ Pico.m.eeprom_status) & 0xc0) // update time only if SDA/SCL changed
- last_write = SekCyclesDone();
- }
- }
- void EEPROM_write8(unsigned int a, unsigned int d)
- {
- unsigned char *wb = Pico.m.eeprom_wb;
- wb[a & 1] = d;
- EEPROM_write16((wb[0] << 8) | wb[1]);
- }
- unsigned int EEPROM_read(void)
- {
- unsigned int shift, d;
- unsigned int sreg, saddr, scyc, ssa, interval;
- // flush last pending write
- EEPROM_write_do(Pico.m.eeprom_status>>6);
- sreg = Pico.m.eeprom_status; saddr = Pico.m.eeprom_addr&0x1fff; scyc = Pico.m.eeprom_cycle; ssa = Pico.m.eeprom_slave;
- interval = SekCyclesDone() - last_write;
- d = (sreg>>6)&1; // use SDA as "open bus"
- // NBA Jam is nasty enough to read <before> raising the SCL and starting the new cycle.
- // this is probably valid because data changes occur while SCL is low and data can be read
- // before it's actual cycle begins.
- if (!(sreg&0x80) && interval >= 24) {
- elprintf(EL_EEPROM, "eeprom: early read, cycles=%i", interval);
- scyc++;
- }
- if (!(sreg & 8)); // not started, use open bus
- else if (scyc == 9 || scyc == 18 || scyc == 27) {
- elprintf(EL_EEPROM, "eeprom: r ack");
- d = 0;
- } else if (scyc > 9 && scyc < 18) {
- // started and first command word received
- shift = 17-scyc;
- if (Pico.sv.eeprom_type) {
- // X24C02+
- if (ssa&1) {
- elprintf(EL_EEPROM, "eeprom: read: addr %02x, cycle %i, reg %02x", saddr, scyc, sreg);
- if (shift==0) elprintf(EL_EEPROM, "eeprom: read done, byte %02x", Pico.sv.data[saddr]);
- d = (Pico.sv.data[saddr]>>shift)&1;
- }
- } else {
- // X24C01
- if (saddr&1) {
- elprintf(EL_EEPROM, "eeprom: read: addr %02x, cycle %i, reg %02x", saddr>>1, scyc, sreg);
- if (shift==0) elprintf(EL_EEPROM, "eeprom: read done, byte %02x", Pico.sv.data[saddr>>1]);
- d = (Pico.sv.data[saddr>>1]>>shift)&1;
- }
- }
- }
- return (d << Pico.sv.eeprom_bit_out);
- }
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