And between those instructions, is there a one, which changes what PORTC pins to use, when sending data out? Except the DATA_ONE and DATA_ZERO defines?
Therefore please look at the caller, which is in this case AsicPushWork in klondike.c, the argument there is DATA_SPLIT, which does the bits for single bank mode. In double bank mode one bank gets a one, the other a zero for MSB. Please also look what exactly the asm code tells, the last lines in send32 function differ from the others.