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GR716-DS-UM, May 2019, Version 1.29
135
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GR716
16.6.6 Register protection control register
ASR register 16 (%asr16) is used to control the IU/FPU register file SEU protection. It is possible to
disable the SEU protection by setting the IDI/FDI bits, and to inject errors using the ITE/FTE bits.
Corrected errors in the register file are counted, and available in ICNT and FCNT fields. The counters
saturate at their maximum value (7), and should be reset by software after read-out.
Table 126.
LEON3FT Register protection control register (%asr16)
31
30
29
27
26
20
19
18
17
16
RESERVED
FCNT
RESERVED
EIUFT
FTE
FDI
0
0
0
1
0
0
r
rw
r
r
rw
r
15
14
13
11
10
3
2
1
0
IUFT
ICNT
RFTB[7:0]
DP
ITE
IDI
1
0
0
0
0
0
r
rw
rw
rw
rw
rw
31:30
Reserved for future implementations
29:27
FP RF error counter - Number of detected parity errors in the FP register file.
26: 20
Reserved for future implementations
19: 18
Extended IU FT ID - Top bits of IUFT field to indicate FT values higher than 3
17
FPU RF Test Enable - Enables FPU register file test mode. Parity bits are xored with TB before writ-
ten to the FPU register file.
16
FP RF protection disable (FDI) - Disables FP RF parity protection when set.
15:14
IU FT ID - SEU protection is available for IU
13:11
IU RF error counter - Number of detected parity errors in the IU register file.
10:3
RF Test bits (RFTB) - In test mode, these bits are xored with correct parity bits before written to the
register file.
2
DP ram select (DP) - Only applicable if the IU or FPU register files consists of two dual-port rams.
See table 127 below.
1
IU RF Test Enable - Enables register file test mode. Parity bits are xored with TB before written to
the register file.
0
IU RF protection disable (IDI) - Disables IU RF parity protection when set.
Table 127.
DP ram select usage
ITE/FTE
DP
Function
1
0
Write to IU register (%i, %l, %o, %g) will only write location of %rs2
Write to FPU register (%f) will only write location of %rs2
1
1
Write to IU register (%i, %l, %o, %g) will only write location of %rs1
Write to FPU register (%f) will only write location of %rs1
0
X
IU and FPU registers written nominally