Visible to Intel only — GUID: bdj1695169342307
Ixiasoft
3.3.6.1.1. Machine Status Register (mstatus)
3.3.6.1.2. Machine Trap-Vector Base-Address Register (mtvec)
3.3.6.1.3. Machine Interrupt Register (mip and mie)
3.3.6.1.4. Machine Exception Program Counter Register (mepc)
3.3.6.1.5. Machine Cause Register (mcause)
3.3.6.1.6. Machine Trap Value Register (mtval)
4.3.1. General-Purpose Register File
4.3.2. Arithmetic Logic Unit
4.3.3. Multipy and Divide Units
4.3.4. Floating-Point Unit
4.3.5. Custom Instruction
4.3.6. Instruction Cycles
4.3.7. Reset and Debug Signals
4.3.8. Control and Status Registers
4.3.9. Trap Controller (CLINT)
4.3.10. Memory and I/O Organization
4.3.11. RISC-V based Debug Module
4.3.12. Error Correction Code (ECC)
4.3.13. Branch Prediction
4.3.14. Lockstep Module
4.3.9.1.1. Machine Status Register (mstatus)
4.3.9.1.2. Machine Trap-Vector Base-Address Register (mtvec)
4.3.9.1.3. Machine Interrupt Register (mip and mie)
4.3.9.1.4. Machine Exception Program Counter Register (mepc)
4.3.9.1.5. Machine Cause Register (mcause)
4.3.9.1.6. Machine Trap Value Register (mtval)
4.3.9.1.7. Machine Second Trap Value Register (mtval2)
Visible to Intel only — GUID: bdj1695169342307
Ixiasoft
4.3.4.2.1. Floating Point Classification
The FCLASS.S instruction classifies the floating-point value into ten possible classifications specified in the following table and returns an integer value.
Classification | Description | Single Precision FP Representation | Return Integer Value | ||
---|---|---|---|---|---|
Sign (1 bit) | Exponent (8 bit) | Mantissa (23 bit) | |||
-infinity | Negative infinity | 1 | 0xFF | 0 | 0 |
-normal | Negative normalized non-zero value | 1 | Any value (except values representing other classes) | 1 | |
-subnormal | Negative denormalized value | 1 | 0 | Non-zero | 2 |
-0 | Negative zero value | 1 | 0 | 0 | 3 |
+0 | Positive zero value | 0 | 0 | 0 | 4 |
+subnormal | Positive denormalized value | 0 | 0 | Non-zero | 5 |
+normal | Positive normalized non-zero value | 0 | Any value (except values representing other classes) | 6 | |
+infinity | Positive infinity | 0 | 0xFF | 0 | 7 |
Signaling NaN | Signaling NaN | Don’t Care | 0xFF | 0x1 to 0x3FFFFF | 8 |
Quiet NaN | Quiet NaN | Don’t Care | 0xFF | 0x400000 to 0x7FFFFF | 9 |