Wii Serial Interface: Dolphin doesn't match real hardware?

Code:
#include <stdio.h>

#include <stdlib.h>

#include <gccore.h>

#include <wiiuse/wpad.h>



static void *xfb = NULL;

static GXRModeObj *rmode = NULL;



vu32* const si_reg = (u32*)0xCD006400;

vu32* const si_buf = (u32*)0xCD006480;



//Generates 32-bit value that can be written to SICOMCSR to start a transfer on a given channel

u32 generate_com_csr(u32 channel, u32 in_len, u32 out_len)

{

    u32 com_csr = 0;



    in_len &= 0x7F;

    out_len &= 0x7F;

    channel &= 0x3;

        

    //Channel

    com_csr |= (channel << 25);



    //Channel Enable

    com_csr |= (1 << 24);



    //Output Length

    com_csr |= (out_len << 16);



    //Input Length

    com_csr |= (in_len << 8);



    //Command Enable

    com_csr |= (1 << 7);



    //Channel 2?

    com_csr |= (channel << 1);



    //Callback Enable

    com_csr |= (0 << 6);



    //TSTART

    com_csr |= 1;



    return com_csr;

}



//Sends the JOYBUS command 0x00 to the given channel

//Used to find out the device ID (written to SI buffer)

void ping_ID(u32 channel)

{

    //Clear SI buffer

    for(int x = 0; x < 0x80; x++) { si_buf[x] = 0; }

    

    //Setup JOYBUS command 0x00

    si_buf[0] = 0x00;



    //Write to SICOMCSR to start transfer, wait for any pending transfers first

    while(si_reg[13] & 0x1) { }

    si_reg[13] = generate_com_csr(channel, 4, 2);



    //Wait for next SICOMCSR transfer to finish

    while(si_reg[13] & 0x1) { }    

}



//---------------------------------------------------------------------------------

int main(int argc, char **argv) {

//---------------------------------------------------------------------------------



    // Initialise the video system

    VIDEO_Init();



    // This function initialises the attached controllers

    WPAD_Init();



    // Obtain the preferred video mode from the system

    // This will correspond to the settings in the Wii menu

    rmode = VIDEO_GetPreferredMode(NULL);



    // Allocate memory for the display in the uncached region

    xfb = MEM_K0_TO_K1(SYS_AllocateFramebuffer(rmode));



    // Initialise the console, required for printf

    console_init(xfb,20,20,rmode->fbWidth,rmode->xfbHeight,rmode->fbWidth*VI_DISPLAY_PIX_SZ);



    // Set up the video registers with the chosen mode

    VIDEO_Configure(rmode);



    // Tell the video hardware where our display memory is

    VIDEO_SetNextFramebuffer(xfb);



    // Make the display visible

    VIDEO_SetBlack(FALSE);



    // Flush the video register changes to the hardware

    VIDEO_Flush();



    // Wait for Video setup to complete

    VIDEO_WaitVSync();

    if(rmode->viTVMode&VI_NON_INTERLACE) VIDEO_WaitVSync();



    u32 loop = 0;

    u32 vcount = 0;



    while(1) {

        vcount++;

    

        if(vcount == 60)

        {

            ping_ID(0);

            u32 id_1 = si_buf[0];



            ping_ID(1);

            u32 id_2 = si_buf[0];



            ping_ID(2);

            u32 id_3 = si_buf[0];



            ping_ID(3);

            u32 id_4 = si_buf[0];



            printf("%x\n", loop++);

            printf("ID 1 -> 0x%x\n", id_1);

            printf("ID 2 -> 0x%x\n", id_2);

            printf("ID 3 -> 0x%x\n", id_3);

            printf("ID 4 -> 0x%x\n\n", id_4);



            vcount = 0;

        }        



        // Call WPAD_ScanPads each loop, this reads the latest controller states

        WPAD_ScanPads();



        // WPAD_ButtonsDown tells us which buttons were pressed in this loop

        // this is a "one shot" state which will not fire again until the button has been released

        u32 pressed = WPAD_ButtonsDown(0);



        // We return to the launcher application via exit

        if ( pressed & WPAD_BUTTON_HOME ) exit(0);



        // Wait for the next frame

        VIDEO_WaitVSync();

    }



    return 0;

}