pokeemerald/src/multiboot.c

#include "gba/gba.h"
#include "multiboot.h"

IWRAM_DATA static u16 MultiBoot_required_data[MULTIBOOT_NCHILD];

static int MultiBootSend(struct MultiBootParam *mp, u16 data);
static int MultiBootHandShake(struct MultiBootParam *mp);
static void MultiBootWaitCycles(u32 cycles);
static void MultiBootWaitSendDone(void);

void MultiBootInit(struct MultiBootParam *mp)
{
    mp->client_bit = 0;
    mp->probe_count = 0;
    mp->response_bit = 0;

    mp->check_wait = MULTIBOOT_CONNECTION_CHECK_WAIT;
    mp->sendflag = 0;

    mp->handshake_timeout = 0;

    REG_RCNT = 0;
    REG_SIOCNT = SIO_MULTI_MODE | SIO_115200_BPS;
    REG_SIODATA8 = 0;
}

int MultiBootMain(struct MultiBootParam *mp)
{
    int i;
    int j;
    int k;

    if (MultiBootCheckComplete(mp))
    {
        return 0;
    }

    if (mp->check_wait > MULTIBOOT_CONNECTION_CHECK_WAIT)
    {
        mp->check_wait--;
        return 0;
    }

output_burst:
    if (mp->sendflag)
    {
        mp->sendflag = 0;

        i = REG_SIOCNT & (SIO_MULTI_BUSY | SIO_ERROR | SIO_ID | SIO_MULTI_SD | SIO_MULTI_SI);
        if (i != SIO_MULTI_SD)
        {
            MultiBootInit(mp);
            return i ^ SIO_MULTI_SD;
        }
    }

    if (mp->probe_count >= 0xe0)
    {
        i = MultiBootHandShake(mp);
        if (i)
        {
            return i;
        }

        if (mp->server_type == MULTIBOOT_SERVER_TYPE_QUICK
         && mp->probe_count > 0xe1
         && MultiBootCheckComplete(mp) == 0)
        {
            MultiBootWaitSendDone();
            goto output_burst;
        }

        if (MultiBootCheckComplete(mp) == 0)
        {
            if (mp->handshake_timeout == 0)
            {
                MultiBootInit(mp);
                return MULTIBOOT_ERROR_HANDSHAKE_FAILURE;
            }
            mp->handshake_timeout--;
        }

        return 0;
    }

    switch (mp->probe_count)
    {
    case 0:
        k = 0x0e;
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            if (*(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2) != 0xffff)
            {
                break;
            }
            k >>= 1;
        }

        k &= 0x0e;
        mp->response_bit = k;

        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
            if (mp->client_bit & (1 << i))
            {
                if (j != ((MULTIBOOT_CLIENT_INFO << 8) | (1 << i)))
                {
                    k = 0;
                    break;
                }
            }
        }

        mp->client_bit &= k;

        if (k == 0)
        {
            mp->check_wait = MULTIBOOT_CONNECTION_CHECK_WAIT;
        }

        if (mp->check_wait)
        {
            mp->check_wait--;
        }
        else
        {
            if (mp->response_bit != mp->client_bit)
            {
                MultiBootStartProbe(mp);
                goto case_1;
            }
        }

    output_master_info:
        return MultiBootSend(mp, (MULTIBOOT_MASTER_INFO << 8) | mp->client_bit);

    case_1:
    case 1:
        mp->probe_target_bit = 0;
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
            if ((j >> 8) == MULTIBOOT_CLIENT_INFO)
            {
                MultiBoot_required_data[i - 1] = j;
                j &= 0xff;
                if (j == (1 << i))
                {
                    mp->probe_target_bit |= j;
                }
            }
        }

        if (mp->response_bit != mp->probe_target_bit)
        {
            goto output_master_info;
        }

        mp->probe_count = 2;
        return MultiBootSend(mp, (MULTIBOOT_MASTER_START_PROBE << 8) | mp->probe_target_bit);

    case 2:
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            if (mp->probe_target_bit & (1 << i))
            {
                j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
                if (j != MultiBoot_required_data[i - 1])
                {
                    mp->probe_target_bit ^= 1 << i;
                }
            }
        }
        goto output_header;

    case 0xd0:
        k = 1;
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
            mp->client_data[i - 1] = j;
            if (mp->probe_target_bit & (1 << i))
            {
                if ((j >> 8) != MULTIBOOT_CLIENT_INFO
                 && (j >> 8) != MULTIBOOT_CLIENT_DLREADY)
                {
                    MultiBootInit(mp);
                    return MULTIBOOT_ERROR_NO_DLREADY;
                }
                if (j == MultiBoot_required_data[i - 1])
                {
                    k = 0;
                }
            }
        }

        if (k == 0)
        {
            return MultiBootSend(mp, (MULTIBOOT_MASTER_REQUEST_DLREADY << 8) | mp->palette_data);
        }

        mp->probe_count = 0xd1;

        k = 0x11;
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            k += mp->client_data[i - 1];
        }
        mp->handshake_data = k;
        return MultiBootSend(mp, (MULTIBOOT_MASTER_START_DL << 8) | (k & 0xff));

    case 0xd1:
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
            if (mp->probe_target_bit & (1 << i))
            {
                if ((j >> 8) != MULTIBOOT_CLIENT_DLREADY)
                {
                    MultiBootInit(mp);
                    return MULTIBOOT_ERROR_NO_DLREADY;
                }
            }
        }

        i = MultiBoot(mp);

        if (i == 0)
        {
            mp->probe_count = 0xe0;
            mp->handshake_timeout = MULTIBOOT_HANDSHAKE_TIMEOUT;
            return 0;
        }
        MultiBootInit(mp);
        mp->check_wait = MULTIBOOT_CONNECTION_CHECK_WAIT * 2;
        return MULTIBOOT_ERROR_BOOT_FAILURE;

    default:
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            if (mp->probe_target_bit & (1 << i))
            {
                j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
                if ((j >> 8) != (MULTIBOOT_MASTER_START_PROBE + 1 - (mp->probe_count >> 1))
                 || ((j & 0xff) != (1 << i)))
                {
                    mp->probe_target_bit ^= 1 << i;
                }
            }
        }

        if (mp->probe_count == 0xc4)
        {
            mp->client_bit = mp->probe_target_bit & 0x0e;
            mp->probe_count = 0;
            goto output_master_info;
        }

    output_header:
        if (mp->probe_target_bit == 0)
        {
            MultiBootInit(mp);
            return MULTIBOOT_ERROR_NO_PROBE_TARGET;
        }

        mp->probe_count += 2;
        if (mp->probe_count == 0xc4)
        {
            goto output_master_info;
        }
        i = MultiBootSend(mp,
            (mp->masterp[mp->probe_count - 4 + 1] << 8)
            | mp->masterp[mp->probe_count - 4]);

        if (i)
        {
            return i;
        }
        if (mp->server_type == MULTIBOOT_SERVER_TYPE_QUICK)
        {
            MultiBootWaitSendDone();
            goto output_burst;
        }
        return 0;
    }
}

static int MultiBootSend(struct MultiBootParam *mp, u16 data)
{
    int i;

    i = REG_SIOCNT & (SIO_MULTI_BUSY | SIO_MULTI_SD | SIO_MULTI_SI);
    if (i != SIO_MULTI_SD)
    {
        MultiBootInit(mp);
        return i ^ SIO_MULTI_SD;
    }

    REG_SIODATA8 = data;
    REG_SIOCNT = SIO_MULTI_MODE | SIO_START | SIO_115200_BPS;

    mp->sendflag = 1;
    return 0;
}

void MultiBootStartProbe(struct MultiBootParam *mp)
{
    if (mp->probe_count != 0)
    {
        MultiBootInit(mp);
        return;
    }
    mp->check_wait = 0;
    mp->client_bit = 0;
    mp->probe_count = 1;
}

void MultiBootStartMaster(struct MultiBootParam *mp, const u8 *srcp, int length, u8 palette_color, s8 palette_speed)
{
    int i = 0;

    if (mp->probe_count != 0
     || mp->client_bit == 0
     || mp->check_wait != 0)
    {
        MultiBootInit(mp);
        return;
    }

    mp->boot_srcp = srcp;
    length = (length + 15) & ~15;
    if (length < MULTIBOOT_SEND_SIZE_MIN || length > MULTIBOOT_SEND_SIZE_MAX)
    {
        MultiBootInit(mp);
        return;
    }

    mp->boot_endp = srcp + length;

    switch (palette_speed)
    {
    case -4:
    case -3:
    case -2:
    case -1:
        i = (palette_color << 3) | (3 - palette_speed);
        break;
    case 0:
        i = 0x38 | palette_color;
        break;
    case 1:
    case 2:
    case 3:
    case 4:
        i = (palette_color << 3) | (palette_speed - 1);
        break;
    }

    mp->palette_data = ((i & 0x3f) << 1) | 0x81;
    mp->probe_count = 0xd0;
}

int MultiBootCheckComplete(struct MultiBootParam *mp)
{
    if (mp->probe_count == 0xe9)
    {
        return 1;
    }

    return 0;
}

static int MultiBootHandShake(struct MultiBootParam *mp)
{
    int i, j;

#define send_data (mp->system_work[0])
#define must_data (mp->system_work[1])

    switch (mp->probe_count)
    {
    case_0xe0:
    case 0xe0:
        mp->probe_count = 0xe1;
        must_data = 0x0000;
        send_data = 0x100000;
        return MultiBootSend(mp, 0x0000);

    default:
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
            if ((mp->client_bit & (1 << i))
                && j != must_data)
            {
                goto case_0xe0;
            }
        }
        mp->probe_count++;
        must_data = send_data & 0xffff;
        if (send_data == 0x0000)
        {
            must_data = mp->masterp[0xac] | (mp->masterp[0xad] << 8);
            send_data = must_data << 5;
        }
        send_data >>= 5;
    output_common:
        return MultiBootSend(mp, send_data);

    case 0xe7:
    case 0xe8:
        for (i = MULTIBOOT_NCHILD; i != 0; i--)
        {
            j = *(vu16 *)(REG_ADDR_SIOMULTI0 + i * 2);
            if ((mp->client_bit & (1 << i)) && j != must_data)
            {
                MultiBootInit(mp);
                return MULTIBOOT_ERROR_HANDSHAKE_FAILURE;
            }
        }

        mp->probe_count++;
        if (mp->probe_count == 0xe9)
        {
            return 0;
        }

        send_data = mp->masterp[0xae] | (mp->masterp[0xaf] << 8);
        must_data = send_data;
        goto output_common;
    }

#undef send_data
#undef must_data
}

static void MultiBootWaitCycles(u32 cycles)
{
    asm("mov r2, pc");
    asm("lsr r2, #24");
    asm("mov r1, #12");
    asm("cmp r2, #0x02");
    asm("beq MultiBootWaitCyclesLoop");

    asm("mov r1, #13");
    asm("cmp r2, #0x08");
    asm("beq MultiBootWaitCyclesLoop");

    asm("mov r1, #4");

    asm("MultiBootWaitCyclesLoop:");
    asm("sub r0, r1");
    asm("bgt MultiBootWaitCyclesLoop");
}

static void MultiBootWaitSendDone(void)
{
    int i;

    for (i = 0; i < 31069; i++)
    {
        if ((REG_SIOCNT & SIO_START) == 0)
        {
            break;
        }
    }

    MultiBootWaitCycles(600);
}