jtag_add_ir_scan() function
@file The JTAG interface can be implemented with a software or hardware fifo. TAP_DRSHIFT and TAP_IRSHIFT are illegal end states; however, TAP_DRSHIFT/IRSHIFT can be emulated as end states, by using longer scans. Code that is relatively insensitive to the path taken through state machine (as long as it is JTAG compliant) can use @a endstate for jtag_add_xxx_scan(). Otherwise, the pause state must be specified as end state and a subsequent jtag_add_pathmove() must be issued. Generate an IR SCAN with a list of scan fields with one entry for each enabled TAP. If the input field list contains an instruction value for a TAP then that is used otherwise the TAP is set to bypass. TAPs for which no fields are passed are marked as bypassed for subsequent DR SCANs.