mirror of https://github.com/raphnet/4nes4snes
340 lines
9.6 KiB
C
340 lines
9.6 KiB
C
/* Name: snes.c
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* Project: Multiple NES/SNES to USB converter
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* Author: Raphael Assenat <raph@raphnet.net>
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* Copyright: (C) 2007 Raphael Assenat <raph@raphnet.net>
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* License: Proprietary, free under certain conditions. See Documentation.
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* Tabsize: 4
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*/
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#define F_CPU 12000000L
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#include <avr/io.h>
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#include <avr/interrupt.h>
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#include <util/delay.h>
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#include <avr/pgmspace.h>
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#include <string.h>
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#include "gamepad.h"
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#include "leds.h"
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#include "snes.h"
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#define REPORT_SIZE 8
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#define GAMEPAD_BYTES 8 /* 2 byte per snes controller * 4 controllers */
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/******** IO port definitions **************/
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#define SNES_LATCH_DDR DDRC
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#define SNES_LATCH_PORT PORTC
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#define SNES_LATCH_BIT (1<<4)
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#define SNES_CLOCK_DDR DDRC
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#define SNES_CLOCK_PORT PORTC
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#define SNES_CLOCK_BIT (1<<5)
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#define SNES_DATA_PORT PORTC
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#define SNES_DATA_DDR DDRC
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#define SNES_DATA_PIN PINC
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#define SNES_DATA_BIT1 (1<<3) /* controller 1 */
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#define SNES_DATA_BIT2 (1<<2) /* controller 2 */
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#define SNES_DATA_BIT3 (1<<1) /* controller 3 */
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#define SNES_DATA_BIT4 (1<<0) /* controller 4 */
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/********* IO port manipulation macros **********/
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#define SNES_LATCH_LOW() do { SNES_LATCH_PORT &= ~(SNES_LATCH_BIT); } while(0)
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#define SNES_LATCH_HIGH() do { SNES_LATCH_PORT |= SNES_LATCH_BIT; } while(0)
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#define SNES_CLOCK_LOW() do { SNES_CLOCK_PORT &= ~(SNES_CLOCK_BIT); } while(0)
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#define SNES_CLOCK_HIGH() do { SNES_CLOCK_PORT |= SNES_CLOCK_BIT; } while(0)
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#define SNES_GET_DATA1() (SNES_DATA_PIN & SNES_DATA_BIT1)
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#define SNES_GET_DATA2() (SNES_DATA_PIN & SNES_DATA_BIT2)
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#define SNES_GET_DATA3() (SNES_DATA_PIN & SNES_DATA_BIT3)
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#define SNES_GET_DATA4() (SNES_DATA_PIN & SNES_DATA_BIT4)
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/*********** prototypes *************/
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static void snesInit(void);
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static void snesUpdate(void);
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static char snesChanged(void);
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static void snesBuildReport(unsigned char *reportBuffer);
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// the most recent bytes we fetched from the controller
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static unsigned char last_read_controller_bytes[GAMEPAD_BYTES];
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// the most recently reported bytes
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static unsigned char last_reported_controller_bytes[GAMEPAD_BYTES];
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// indicates if a controller is in NES mode
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static unsigned char nesMode=0; /* Bit0: controller 1, Bit1: controller 2...*/
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static void snesInit(void)
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{
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unsigned char sreg;
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sreg = SREG;
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cli();
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// clock and latch as output
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SNES_LATCH_DDR |= SNES_LATCH_BIT;
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SNES_CLOCK_DDR |= SNES_CLOCK_BIT;
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// data as input
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SNES_DATA_DDR &= ~(SNES_DATA_BIT1 | SNES_DATA_BIT2 | SNES_DATA_BIT3 | SNES_DATA_BIT4 );
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// enable pullup. This should prevent random toggling of pins
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// when no controller is connected.
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SNES_DATA_PORT |= (SNES_DATA_BIT1 | SNES_DATA_BIT2 | SNES_DATA_BIT3 | SNES_DATA_BIT4 );
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// clock is normally high
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SNES_CLOCK_PORT |= SNES_CLOCK_BIT;
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// LATCH is Active HIGH
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SNES_LATCH_PORT &= ~(SNES_LATCH_BIT);
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nesMode = 0;
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snesUpdate();
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/* Snes controller buttons are sent in this order:
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* 1st byte: B Y SEL START UP DOWN LEFT RIGHT
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* 2nd byte: A X L R 1 1 1 1
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*
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* Nes controller buttons are sent in this order:
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* One byte: A B SEL START UP DOWN LEFT RIGHT
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*
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* When an additional byte is read from a NES controller,
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* all bits are 0. Because the data signal is active low,
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* this corresponds to pressed buttons. When we read
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* from the controller for the first time, detect NES
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* controllers by checking those 4 bits.
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**/
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if (last_read_controller_bytes[1]==0xFF)
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nesMode |= 1;
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if (last_read_controller_bytes[3]==0xFF)
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nesMode |= 2;
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if (last_read_controller_bytes[5]==0xFF)
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nesMode |= 4;
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/* The last controllers are always in NES mode. But
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* it is accessible only of the third is in NES mode
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* too. */
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if (last_read_controller_bytes[7]==0xFF)
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nesMode |= 8;
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SREG = sreg;
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}
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/*
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*
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Clock Cycle Button Reported
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=========== ===============
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1 B
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2 Y
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3 Select
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4 Start
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5 Up on joypad
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6 Down on joypad
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7 Left on joypad
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8 Right on joypad
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9 A
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10 X
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11 L
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12 R
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13 none (always high)
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14 none (always high)
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15 none (always high)
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16 none (always high)
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*
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*/
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static void snesUpdate(void)
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{
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int i;
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unsigned char tmp1=0;
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unsigned char tmp2=0;
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unsigned char tmp3=0;
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unsigned char tmp4=0;
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SNES_LATCH_HIGH();
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_delay_us(12);
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SNES_LATCH_LOW();
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for (i=0; i<8; i++)
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{
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_delay_us(6);
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SNES_CLOCK_LOW();
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tmp1 <<= 1;
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tmp2 <<= 1;
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tmp3 <<= 1;
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tmp4 <<= 1;
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if (!SNES_GET_DATA1()) { tmp1 |= 1; }
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if (!SNES_GET_DATA2()) { tmp2 |= 1; }
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if (!SNES_GET_DATA3()) { tmp3 |= 1; }
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if (!SNES_GET_DATA4()) { tmp4 |= 1; }
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_delay_us(6);
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SNES_CLOCK_HIGH();
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}
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last_read_controller_bytes[0] = tmp1;
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last_read_controller_bytes[2] = tmp2;
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last_read_controller_bytes[4] = tmp3;
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last_read_controller_bytes[6] = tmp4;
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for (i=0; i<8; i++)
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{
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_delay_us(6);
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SNES_CLOCK_LOW();
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// notice that this is different from above. We
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// want the bits to be in reverse-order
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tmp1 >>= 1;
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tmp2 >>= 1;
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tmp3 >>= 1;
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tmp4 >>= 1;
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if (!SNES_GET_DATA1()) { tmp1 |= 0x80; }
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if (!SNES_GET_DATA2()) { tmp2 |= 0x80; }
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if (!SNES_GET_DATA3()) { tmp3 |= 0x80; }
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if (!SNES_GET_DATA4()) { tmp4 |= 0x80; }
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_delay_us(6);
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SNES_CLOCK_HIGH();
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}
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/* Force extra bits to 0 when in NES mode. Otherwise, if
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* we read zeros on the wire, we will have permanantly
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* pressed buttons */
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last_read_controller_bytes[1] = (nesMode & 1) ? 0x00 : tmp1;
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last_read_controller_bytes[3] = (nesMode & 2) ? 0x00 : tmp2;
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last_read_controller_bytes[5] = (nesMode & 4) ? 0x00 : tmp3;
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last_read_controller_bytes[7] = (nesMode & 8) ? 0x00 : tmp4;
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}
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static char snesChanged(void)
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{
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static int first = 1;
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if (first) { first = 0; return 1; }
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return memcmp(last_read_controller_bytes,
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last_reported_controller_bytes, GAMEPAD_BYTES);
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}
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static char getX(unsigned char nesByte1)
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{
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char x = 128;
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if (nesByte1&0x1) { x = 255; }
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if (nesByte1&0x2) { x = 0; }
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return x;
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}
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static char getY(unsigned char nesByte1)
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{
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char y = 128;
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if (nesByte1&0x4) { y = 255; }
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if (nesByte1&0x8) { y = 0; }
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return y;
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}
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static unsigned char snesReorderButtons(unsigned char bytes[2])
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{
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unsigned char v;
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/* pack the snes button bits, which are on two bytes, in
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* one single byte. */
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v = (bytes[0]&0x80)>>7;
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v |= (bytes[0]&0x40)>>5;
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v |= (bytes[0]&0x20)>>3;
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v |= (bytes[0]&0x10)>>1;
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v |= (bytes[1]&0x0f)<<4;
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return v;
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}
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static void snesBuildReport(unsigned char *reportBuffer)
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{
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/* last_read_controller_bytes[] structure:
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*
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* [0] : controller 1, 8 first bits (dpad + start + sel + y|a + b)
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* [1] : controller 1, 8 snes extra bits (4 lower bits are buttons)
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*
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* [2] : controller 2, 8 first bits
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* [3] : controller 2, 4 extra snes buttons
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*
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* [4] : controller 3, 8 first bits
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* [5] : controller 3, 4 extra snes buttons
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*
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* [6] : controller 4, 8 first bits
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* [7] : controller 4, 4 extra snes buttons
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*/
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if (reportBuffer != NULL)
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{
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reportBuffer[0]=getX(last_read_controller_bytes[0]);
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reportBuffer[1]=getY(last_read_controller_bytes[0]);
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reportBuffer[2]=getX(last_read_controller_bytes[2]);
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reportBuffer[3]=getY(last_read_controller_bytes[2]);
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reportBuffer[4] = snesReorderButtons(&last_read_controller_bytes[0]);
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reportBuffer[5] = snesReorderButtons(&last_read_controller_bytes[2]);
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if (nesMode & 0x04) {
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// Two last controllers are in NES mode.
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reportBuffer[6] = last_read_controller_bytes[4];
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reportBuffer[7] = last_read_controller_bytes[6];
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}
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else {
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// Third controller is in SNES mode. Use the two
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// last bytes for it. Sorry, no fourth controller.
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reportBuffer[6] = last_read_controller_bytes[4];
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reportBuffer[7] = last_read_controller_bytes[5];
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}
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}
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memcpy(last_reported_controller_bytes,
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last_read_controller_bytes,
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GAMEPAD_BYTES);
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}
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const char snes_usbHidReportDescriptor[] PROGMEM = {
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0x05, 0x01, // USAGE_PAGE (Generic Desktop)
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0x09, 0x04, // USAGE (Joystick)
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0xa1, 0x01, // COLLECTION (Application)
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0x09, 0x01, // USAGE (Pointer)
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0xa1, 0x00, // COLLECTION (Physical)
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0x09, 0x30, // USAGE (X)
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0x09, 0x31, // USAGE (Y)
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0x09, 0x32, // USAGE (Z)
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0x09, 0x36, // USAGE (SLIDER)
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0x15, 0x00, // LOGICAL_MINIMUM (0)
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0x26, 0xff, 0x00, // LOGICAL_MAXIMUM (255)
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0x75, 0x08, // REPORT_SIZE (8)
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0x95, 0x04, // REPORT_COUNT (4)
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0x81, 0x02, // INPUT (Data,Var,Abs)
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0xc0, // END_COLLECTION
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0x05, 0x09, // USAGE_PAGE (Button)
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0x19, 1, // USAGE_MINIMUM (Button 1)
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0x29, 32, // USAGE_MAXIMUM (Button 32)
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0x15, 0x00, // LOGICAL_MINIMUM (0)
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0x25, 0x01, // LOGICAL_MAXIMUM (1)
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0x75, 1, // REPORT_SIZE (1)
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0x95, 32, // REPORT_COUNT (32)
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0x81, 0x02, // INPUT (Data,Var,Abs)
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0xc0 // END_COLLECTION
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};
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Gamepad SnesGamepad = {
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report_size: REPORT_SIZE,
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reportDescriptorSize: sizeof(snes_usbHidReportDescriptor),
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init: snesInit,
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update: snesUpdate,
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changed: snesChanged,
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buildReport: snesBuildReport
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};
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Gamepad *snesGetGamepad(void)
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{
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SnesGamepad.reportDescriptor = (void*)snes_usbHidReportDescriptor;
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return &SnesGamepad;
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}
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