133 lines
3.2 KiB
C
133 lines
3.2 KiB
C
#include "gameboy.h"
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//only need this file if connector is present on the device
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#ifdef GB_CONN
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//=================================================================================================
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//
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// GAMEBOY operations
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// This file includes all the gameboy functions possible to be called from the gameboy dictionary.
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//
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// See description of the commands contained here in shared/shared_dictionaries.h
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//
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//=================================================================================================
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/* Desc:Function takes an opcode which was transmitted via USB
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* then decodes it to call designated function.
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* shared_dict_gameboy.h is used in both host and fw to ensure opcodes/names align
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* Pre: Macros must be defined in firmware pinport.h
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* opcode must be defined in shared_dict_gameboy.h
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* Post:function call complete.
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* Rtn: SUCCESS if opcode found and completed, error if opcode not present or other problem.
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*/
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uint8_t gameboy_call( uint8_t opcode, uint8_t miscdata, uint16_t operand, uint8_t *rdata )
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{
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#define RD_LEN 0
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#define RD0 1
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#define RD1 2
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#define BYTE_LEN 1
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#define HWORD_LEN 2
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switch (opcode) {
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// //no return value:
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case DMG_WR:
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dmg_wr( operand, miscdata );
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break;
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//8bit return values:
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case DMG_RD:
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rdata[RD_LEN] = BYTE_LEN;
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rdata[RD0] = dmg_rd( operand );
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break;
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default:
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//macro doesn't exist
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return ERR_UNKN_GAMEBOY_OPCODE;
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}
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return SUCCESS;
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}
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uint8_t dmg_rd( uint16_t addr )
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{
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return 0xAA;
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}
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void dmg_wr( uint16_t addr, uint8_t data )
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{
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return;
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}
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/* Desc:GAMEBOY 8bit CPU Page Read with optional USB polling
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* decode A15 from addrH to set SRAM /CE as expected
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* if poll is true calls usbdrv.h usbPoll fuction
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* this is needed to keep from timing out when double buffering usb data
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* Pre: gameboy_init() setup of io pins
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* num_bytes can't exceed 256B page boundary
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* Post:address left on bus
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* data bus left clear
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* data buffer filled starting at first to last
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* Rtn: Index of last byte read
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*/
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uint8_t gameboy_page_rd_poll( uint8_t *data, uint8_t addrH, uint8_t first, uint8_t len, uint8_t poll )
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{
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uint8_t i;
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//set address bus
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ADDRH(addrH);
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//enable /RD pin
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CSRD_LO();
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//set SRAM /CS
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//low for $A000-BFFF
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if( (addrH >= 0xA0) && (addrH <= 0xBF) ) { //addressing cart RAM space
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ROMSEL_LO(); //this is actually the SRAM /CS pin
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}
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//set lower address bits
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ADDRL(first); //doing this prior to entry and right after latching
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//extra NOP was needed on stm6 as address hadn't settled in time for the very first read
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NOP();
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//gives longest delay between address out and latching data
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for( i=0; i<=len; i++ ) {
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//testing shows that having this if statement doesn't affect overall dumping speed
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if ( poll ) {
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usbPoll(); //Call usbdrv.h usb polling while waiting for data
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} else {
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NOP(); //couple more NOP's waiting for data
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NOP(); //one prob good enough considering the if/else
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}
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//gameboy needed some extra NOPS
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NOP();
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NOP();
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NOP();
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NOP();
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NOP();
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NOP();
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//latch data
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DATA_RD(data[i]);
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//set lower address bits
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//ADDRL(++first); THIS broke things, on stm adapter because macro expands it twice!
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first++;
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ADDRL(first);
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}
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//return bus to default
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CSRD_HI();
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ROMSEL_HI();
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//return index of last byte read
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return i;
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}
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#endif //GB_CONN
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