MIPS Register packet Format (Debugging with GDB)

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Gdb/docs/latest/gdb/MIPS-Register-packet-Format


E.5.2.1 MIPS Register Packet Format

The following g/G packets have previously been defined. In the below, some thirty-two bit registers are transferred as sixty-four bits. Those registers should be zero/sign extended (which?) to fill the space allocated. Register bytes are transferred in target byte order. The two nibbles within a register byte are transferred most-significant – least-significant.

MIPS32
All registers are transferred as thirty-two bit quantities in the order: 32 general-purpose; sr; lo; hi; bad; cause; pc; 32 floating-point registers; fsr; fir; fp.
MIPS64
All registers are transferred as sixty-four bit quantities (including thirty-two bit registers such as sr). The ordering is the same as MIPS32.