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Expain how the bit order works and how get the opcode. The IBM and freescale manual for ppc cpu are not good expain it.

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now I got less headic, and got understainf how to decoding the manual and how the opcode are store. 
  

svn path=/trunk/; revision=25507
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Magnus Olsen 2007-01-18 13:43:17 +00:00
parent 4da115c6b5
commit 48cd2b3e75
1 changed files with 37 additions and 2 deletions
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39
rosapps/devutils/cputointel/OpCodePPC.txt
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@ -9,9 +9,44 @@ Bit expain
1 = mean bit is set
2 = mean this bit can be 0 or 1
opcode Name Desciptions
opcode Name Desciptions
0010 0000 0000 0000 1000 0000 0100 1110 blr return from a functions
0222 2222 2222 2222 2222 2222 0011 1000 Li reg,#imm move a value to a register
Here how the primary opcode work
xxxx xxxx xxxx xxxx DDDS SSSS 3333 33DD
3 = it is the primary opcode
D = Destions register
S = Source reigters
opcode
------------------------
|bit order: 0123 45 67|
------- ------- ----------- ----
34: | 0c 00 | | e1 93 | stw r31,12(r1) 0000 1100 0000 0000 1110 0001 | 1001 00 | 00
38: | 14 00 | | 01 90 | stw r0,20(r1) 0001 0100 0000 0000 0000 0001 | 1001 00 | 11
------- ------- ---------
| |
| |--> Get source register R0-R31 (0xE1 & 0x1F) = 1
| |
| |--> Get Dest register R0-R31 ((0xE1 & 0xE0)>>5) | ((0x90 & 0x3)<<3) = 31 or 0
| | (The adding the two last bit on the end is maybe wrong need examine it)
| |
| --> Get the opcpde (0x90 & 0xFC)
\ /
The address offset 12 or 20
---------------------------------------------------------
|bit order: pos 1111 1111 1111 1111 0000 0000 0000 0000 |
| 89AB CDEF 0123 4567 89AB CDEF 0123 4567 |
|---------------------------------------------------------|
| bits 0000 1100 0000 0000 1110 0001 1001 0000 |
---------------------------------------------------------