/* This file is included into vb.c and cannot be compiled on its own. */
#ifdef VBAPI



/***************************** Utility Functions *****************************/

/* Read a typed value from a buffer in host memory */
static int32_t busReadBuffer(
    uint8_t *buffer, uint32_t size, uint32_t offset, int type) {

    /* There is no data */
    if (buffer == NULL)
        return 0;

    /* Mirror the buffer across its address range */
    offset &= size - 1;

    /* Processing by type */
    switch (type) {

        /* Generic implementation */
        #ifndef VB_LITTLE_ENDIAN
            case VB_S8 :
                return (int8_t) buffer[offset];
            case VB_U8:
                return buffer[offset];
            case VB_S16:
                return (int32_t) (int8_t)
                    buffer[offset + 1] << 8 | buffer[offset];
            case VB_U16:
                offset &= 0xFFFFFFFE;
                return (int32_t) (int8_t)
                    buffer[offset + 1] << 8 | buffer[offset];
            case VB_S32:
                offset &= 0xFFFFFFFC;
                return
                    (int32_t) buffer[offset + 3] << 24 |
                    (int32_t) buffer[offset + 2] << 16 |
                    (int32_t) buffer[offset + 1] <<  8 |
                              buffer[offset    ]
                ;

        /* Little-endian implementation */
        #else
            case VB_S8 : return *(int8_t   *)&buffer[offset             ];
            case VB_U8 : return               buffer[offset             ];
            case VB_S16: return *(int16_t  *)&buffer[offset & 0xFFFFFFFE];
            case VB_U16: return *(uint16_t *)&buffer[offset & 0xFFFFFFFE];
            case VB_S32: return *(int32_t  *)&buffer[offset & 0xFFFFFFFC];
        #endif

    }

    /* Invalid type */
    return 0;
}

/* Write a typed value to a buffer in host memory */
static void busWriteBuffer(
    uint8_t *buffer, uint32_t size, uint32_t offset, int type, int32_t value) {

    /* There is no data */
    if (buffer == NULL)
        return;

    /* Mirror the buffer across its address range */
    offset &= size - 1;

    /* Processing by type */
    switch (type) {

        /* Generic implementation */
        #ifndef VB_LITTLE_ENDIAN
            case VB_S32:
                offset &= 0xFFFFFFFC;
                buffer[offset    ] = value;
                buffer[offset + 1] = value >>  8;
                buffer[offset + 2] = value >> 16;
                buffer[offset + 3] = value >> 24;
                break;
            case VB_S16:
            case VB_U16:
                offset &= 0xFFFFFFFE;
                buffer[offset    ] = value;
                buffer[offset + 1] = value >> 8;
                break;
            case VB_S8 :
            case VB_U8 :
                buffer[offset    ] = value;

        /* Little-endian implementation */
        #else
            case VB_S8 :
            case VB_U8 :
                buffer[offset                          ] = value;
                break;
            case VB_S16:
            case VB_U16:
                *(int16_t *)&buffer[offset & 0xFFFFFFFE] = value;
                break;
            case VB_S32:
                *(int32_t *)&buffer[offset & 0xFFFFFFFC] = value;
        #endif

    }

}



/***************************** Module Functions ******************************/

/* Read a typed value from the simulation bus */
static int32_t busRead(VB *sim, uint32_t address, int type) {

    /* Processing by address region */
    switch (address >> 24 & 7) {
        case 0: return 0; /* VIP */
        case 1: return 0; /* VSU */
        case 2: return 0; /* Misc. hardware */
        case 3: return 0; /* Unmapped */
        case 4: return 0; /* Game pak expansion */
        case 5: return    /* WRAM */
            busReadBuffer(sim->wram    , 0x10000          , address, type);
        case 6: return    /* Game pak RAM */
            busReadBuffer(sim->cart.ram, sim->cart.ramSize, address, type);
        case 7: return    /* Game pak ROM */
            busReadBuffer(sim->cart.rom, sim->cart.romSize, address, type);
    }

    /* Unreachable */
    return 0;
}

/* Write a typed value to the simulation bus */
static void busWrite(VB*sim,uint32_t address,int type,int32_t value,int debug){
    (void) debug;

    /* Processing by address region */
    switch (address >> 24 & 7) {
        case 0: break; /* VIP */
        case 1: break; /* VSU */
        case 2: break; /* Misc. hardware */
        case 3: break; /* Unmapped */
        case 4: break; /* Game pak expansion */
        case 5:        /* WRAM */
            busWriteBuffer(sim->wram    ,0x10000          ,address,type,value);
            break;
        case 6:        /* Game pak RAM */
            busWriteBuffer(sim->cart.ram,sim->cart.ramSize,address,type,value);
            break;
        case 7:        /* Game pak ROM */
            busWriteBuffer(sim->cart.rom,sim->cart.romSize,address,type,value);
            break;
    }

}



#endif /* VBAPI */