loader again

#include <z64ovl/oot/u10.h>

typedef struct {
    z64_actor_t actor;
} entity_t;

typedef union {
    struct { // meta commands
        union {
            struct { // set up data pointer
                volatile u8* ptr;
                u8  pad[6];
            } c00_data;
            struct { // write <= 9 bytes
                u8 bytes[ 9 ];
                u8 count;
            } c01_data;
            struct { // write N zeroes
                u32 number_of_zeroes;
                u8  padding[ 6 ];
            } c02_data;
            struct { // checksum/ack/nak
                // ?????
            } c03_data;
            struct { // jump to given function pointer
                void (*func_pointer)(void);
                u8 padding[ 6 ];
            } c04_data;
            u8 bytes[ 10 ];
        };
        u8 meta_command;
    } meta;
    struct { // DMA
        u32* dest_ram;
        u32* src_vrom;
        u32  size:24;
    } lowlevel;
    u8  bytes[ 12 ]; // last byte is padding
} pad_data_t;
// 12 bytes long

// ????
void (*const DmaMgr_SendRequest0)( u32* vram_addr, u32* vrom_addr, u32 size ) = (const void*)0x80001AA0;

static volatile u8* data_pointer;
static pad_data_t pad;

static void step( entity_t* entity, z64_global_t* global ) {
    #define padb( pad, byte ) ( ((u8*)&(global->common.input[ pad ].raw))[ byte ] )

    register union {
        struct {
            u8 big_endian_padding;
            u8 ll_command;
            u8 byte2;
            u8 byte1;
        };
        u32 word;
    } leftover;

    // only run if all pads are connected and working
    if( global->common.input[ 1 ].status != 0 || global->common.input[ 2 ].status != 0 || global->common.input[ 3 ].status != 0 )
        return;

    pad.bytes[ 0 ] = padb( 1, 0 );
    pad.bytes[ 1 ] = padb( 1, 2 );
    pad.bytes[ 2 ] = padb( 1, 3 );
    pad.bytes[ 3 ] = padb( 2, 0 );
    pad.bytes[ 4 ] = padb( 2, 2 );
    pad.bytes[ 5 ] = padb( 2, 3 );
    pad.bytes[ 6 ] = padb( 3, 0 );
    pad.bytes[ 7 ] = padb( 3, 2 );
    pad.bytes[ 8 ] = padb( 3, 3 );

    leftover.word   = padb( 1, 1 );
    leftover.word <<= 6;
    leftover.word  |= padb( 2, 1 );
    leftover.word <<= 6;
    leftover.word  |= padb( 3, 1 );
    pad.bytes[  9 ] = leftover.byte1;
    pad.bytes[ 10 ] = leftover.byte2;

    switch( leftover.ll_command ) {
        case 0: break; // NOP
        case 1: { // load 11 bytes
            u8 i;
            for( i = 0; i < 11; ++i )
                *(data_pointer++) = pad.bytes[ i ];
        } break;
        case 2: { // DMA copy
            DmaMgr_SendRequest0( pad.lowlevel.dest_ram, pad.lowlevel.src_vrom, pad.lowlevel.size );
        } break;
        case 3: {
            // -----------------------------------------------
            switch( pad.meta.meta_command ) {
                case  0: { // load data pointer
                    data_pointer = pad.meta.c00_data.ptr;
                } break;
                case  1: { // write <= 9 bytes
                    u8 i;
                    for( i = 0; i < pad.meta.c01_data.count; ++i )
                        *( data_pointer++ ) = pad.meta.c01_data.bytes[ i ];
                } break;
                case  2: { // write N zeroes
                    while( pad.meta.c02_data.number_of_zeroes > 0 ) {
                        *( data_pointer++ ) = 0;
                        --pad.meta.c02_data.number_of_zeroes;
                    }
                } break;
                case  3: { // error correction
                    // ????
                } break;
                case  4: { // jump to address
                    pad.meta.c04_data.func_pointer();
                } break;
                default: break;
            }
            // -----------------------------------------------
        } break;
        default: break; // this should never happen
    }
}

const z64_actor_init_t init_vars = {
    .number = 0xDEAD, .padding = 0xBEEF,
    .type = 0x06, // stage prop
    .room = 0x00,
    .flags = 0x00000030,
    .object = 1,
    .instance_size = sizeof(entity_t),
    .init = NULL,
    .dest = NULL,
    .main = step,
    .draw = NULL
};