* mips.h: Improve comments describing the bitfield instruction

fields.
This commit is contained in:
Thiemo Seufer 2006-04-26 18:19:15 +00:00
parent 330a2faed9
commit 564d770d9a
2 changed files with 12 additions and 6 deletions

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@ -1,3 +1,8 @@
2006-04-26 Thiemo Seufer <ths@networkno.de>
* mips.h: Improve comments describing the bitfield instruction
fields.
2006-04-07 Joerg Wunsch <j.gnu@uriah.heep.sax.de>
* avr.h (AVR_ISA_PWMx): New.

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@ -268,19 +268,20 @@ struct mips_opcode
"x" accept and ignore register name
"z" must be zero register
"K" 5 bit Hardware Register (rdhwr instruction) (OP_*_RD)
"+A" 5 bit ins/ext position, which becomes LSB (OP_*_SHAMT).
"+A" 5 bit ins/ext/dins/dext/dinsm/dextm position, which becomes
LSB (OP_*_SHAMT).
Enforces: 0 <= pos < 32.
"+B" 5 bit ins size, which becomes MSB (OP_*_INSMSB).
"+B" 5 bit ins/dins size, which becomes MSB (OP_*_INSMSB).
Requires that "+A" or "+E" occur first to set position.
Enforces: 0 < (pos+size) <= 32.
"+C" 5 bit ext size, which becomes MSBD (OP_*_EXTMSBD).
"+C" 5 bit ext/dext size, which becomes MSBD (OP_*_EXTMSBD).
Requires that "+A" or "+E" occur first to set position.
Enforces: 0 < (pos+size) <= 32.
(Also used by "dext" w/ different limits, but limits for
that are checked by the M_DEXT macro.)
"+E" 5 bit dins/dext position, which becomes LSB-32 (OP_*_SHAMT).
"+E" 5 bit dinsu/dextu position, which becomes LSB-32 (OP_*_SHAMT).
Enforces: 32 <= pos < 64.
"+F" 5 bit "dinsm" size, which becomes MSB-32 (OP_*_INSMSB).
"+F" 5 bit "dinsm/dinsu" size, which becomes MSB-32 (OP_*_INSMSB).
Requires that "+A" or "+E" occur first to set position.
Enforces: 32 < (pos+size) <= 64.
"+G" 5 bit "dextm" size, which becomes MSBD-32 (OP_*_EXTMSBD).