Functional Peripherals Registers
168
SLAU356I – March 2015 – Revised June 2019
Copyright © 2015–2019, Texas Instruments Incorporated
Cortex-M4F Peripherals
2.4.5.29 ISAR4 Register (Offset = D70h) [reset = 01310132h]
ISAR4 is shown in
and described in
ISA Feature register4. Information on the instruction set attributes register
Figure 2-79. ISAR4 Register
31
30
29
28
27
26
25
24
RESERVED
PSR_M_INSTRS
R-0h
R-1h
23
22
21
20
19
18
17
16
SYNCPRIM_INSTRS_FRAC
BARRIER_INSTRS
R-3h
R-1h
15
14
13
12
11
10
9
8
RESERVED
WRITEBACK_INSTRS
R-0h
R-1h
7
6
5
4
3
2
1
0
WITHSHIFTS_INSTRS
UNPRIV_INSTRS
R-0h
R-2h
Table 2-87. ISAR4 Register Field Descriptions
Bit
Field
Type
Reset
Description
31-28
RESERVED
R
0h
27-24
PSR_M_INSTRS
R
1h
PSR_M_instrs
0b (R/W) = instructions not present
1b (R/W) = adds CPS, MRS, and MSR instructions (M-profile forms)
23-20
SYNCPRIM_INSTRS_FR
AC
R
3h
SyncPrim_instrs_frac
0b (R/W) = no additional support
11b (R/W) = adds CLREX, LDREXB, STREXB, LDREXH, STREXH
19-16
BARRIER_INSTRS
R
1h
Barrier instructions
0b (R/W) = no barrier instructions supported
1b (R/W) = adds DMB, DSB, ISB barrier instructions
15-12
RESERVED
R
0h
11-8
WRITEBACK_INSTRS
R
1h
Writeback instructions
0b (R/W) = only non-writeback addressing modes present, except
that LDMIA/STMDB/PUSH/POP instructions support writeback
addressing.
1b (R/W) = adds all currently-defined writeback addressing modes
(ARMv7, Thumb-2)
7-4
WITHSHIFTS_INSTRS
R
3h
WithShift instructions. Note that all additions only apply in cases
where the encoding supports them; for example, there is no
difference between levels 3 and 4 in the Thumb-2 instruction set.
MOV instructions with shift options should instead be treated as
ASR, LSL, LSR, ROR or RRX instructions.
000b (R/W) = non-zero shifts only support MOV and shift instructions
001b (R/W) = shifts of loads/stores over the range LSL 0-3
011b (R/W) = adds other constant shift options.
100b (R/W) = adds register-controlled shift options.
3-0
UNPRIV_INSTRS
R
2h
Unprivileged instructions
00b (R/W) = no "T variant" instructions exist
01b (R/W) = adds LDRBT, LDRT, STRBT, STRT
10b (R/W) = adds LDRHT, LDRSBT, LDRSHT, STRHT