vxsat
Vector Fixed-Point Saturate Flag
Indicates if a fixed-point instruction has had to saturate an output value to fit into a destination format
Attributes
Requirement |
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|---|---|---|---|
Defining extensions |
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CSR Address |
0x9 |
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Length |
* 32 when (priv_mode() == PrivilegeMode::M && CSR[misa].MXL == 0) || (priv_mode() == PrivilegeMode::S && CSR[mstatus].SXL == 0) || (priv_mode() == PrivilegeMode::U && CSR[mstatus].UXL == 0) || (priv_mode() == PrivilegeMode::VS && CSR[hstatus].VSXL == 0) || (priv_mode() == PrivilegeMode::VU && CSR[vsstatus].UXL == 0) * 64 when (priv_mode() == PrivilegeMode::M && CSR[misa].MXL == 1) || (priv_mode() == PrivilegeMode::S && CSR[mstatus].SXL == 1) || (priv_mode() == PrivilegeMode::U && CSR[mstatus].UXL == 1) || (priv_mode() == PrivilegeMode::VS && CSR[hstatus].VSXL == 1) || (priv_mode() == PrivilegeMode::VU && CSR[vsstatus].UXL == 1) |
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Privilege Mode |
U |
Format
This CSR format changes dynamically.
Field Summary
| Name | Location | Type | Reset Value |
|---|---|---|---|
* 31:0 when CSR[mstatus].UXL == 0 * 63:0 when CSR[mstatus].UXL == 1 |
RW-H |
UNDEFINED_LEGAL |
Fields
VALUE
- Location
-
-
31:0 when CSR[mstatus].UXL == 0
-
63:0 when CSR[mstatus].UXL == 1
-
- Description
-
The vxsat CSR has a single read-write least-significant bit (vxsat[0]) that indicates if a fixed-point instruction has had to saturate an output value to fit into a destination format. Bits vxsat[XLEN-1:1] should be written as zeros.
The vxsat bit is mirrored in vcsr.
- Type
-
RW-H
- Reset value
-
UNDEFINED_LEGAL
Software write
This CSR may store a value that is different from what software attempts to write.
When a software write occurs (e.g., through csrrw), the following determines the written value:
VALUE = return csr_value.VALUE & 1;