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QuadCore Team – DLX ISA. David Bild Greg Bok Jake Czyz Brandon Keao. Floating-Point Instructions. There are three categories for the DLX floating-point instructions: Arithmetic Conversion Set-on-comparison All operation occur in the floating-point registers and are in the R-type format. - PowerPoint PPT Presentation
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QuadCore Team – DLX ISA
David Bild Greg Bok Jake Czyz Brandon Keao
Floating-Point Instructions
There are three categories for the DLX floating-point instructions: Arithmetic Conversion Set-on-comparison
All operation occur in the floating-point registers and are in the R-type format.
DLX ISA
Floating-Point Instructions: Arithmetic
Brandon Keao
Floating-Point Instructions: Arithmetic
These intructions preform arithmetic operations on two floating-point registers
Always R-format There are 2 categories of floating-point
arithmetic instructions: Single-precision Double-precision
Floating-Point Instructions: Arithmetic
SP operations interpret the values in the two registers as SP FP values
The result is rounded to a SP value and stored in a FP register ADDF- Adds two SP values SUBF - Subtracts two SP values MULTF - Multiplies two SP values DIVF - Divides two SP values
Floating-Point Instructions: Arithmetic
DP operations interpret the values of two even/odd pairs of FP registers as DP FP values.
The result if rounded to a DP value and stored in an even/odd pair of FP registers. ADDD - Adds two DP values SUBD - Subtracts two DP values MULTD - Multiplies two DP values DIVD - Divides two DP values
DLX ISA
Floating-Point Instructions: Conversion
And Special Instructions
Greg Bok
Floating-Point Instructions: Conversion
Sometimes need to convert between precisions or integer/floating-point
The DLX ISA includes 6 such instructions R-format Double-precision FP register operands
must be even-numbered FP registers 32-bit integers used
Floating-Point Instructions: Conversion
1. CVT2DF: double-precision to single-precision
2. CVTD2I: double-precision to integer
3. CVTF2D: single-precision to double-precision
4. CVTF2I: single-precision to integer
5. CVTI2D: integer to double-precision
6. CVTI2F: integer to single-precision
Special Instructions: TRAP J-type, unconditional branch 26-bit name field zero-extended to 32-
bits to obtain target address Moves PC + 8 to IAR (interrupt address
register)
Special Instructions: RFE Return From Exception J-type, unconditional Returns to code that was executing
before TRAP instruction Moves value in IAR register to PC
Special Instructions: NOP R-type Performs no operation -- hardware state
is unaffected Typically used to fill branch delay slots
when no useful instruction will work
DLX ISA
Floating-Point Instructions: Set-on-Comparison
David Bild
Floating-Point Instructions: Set-On-Comparison
Compares two floating point numbers (SP or DP)
Sets FPSR (Floating Point Status Register) to ‘1’ if comparison is true, ‘0’ if false
6 comparisons are provided: <, >, =. <=, >=, ~=
DLX ISA
Load & Store Instructions
Jake Czyz
Load and Store Instructions For loading/storing data from/to memory Handle data of size:
Byte Halfword Word Double (for floating point only)
Load and Store Instructions Byte and Halfword instructions always
load/store the least significant byte or halfword, respectively.
Loads and Stores may be done with any of the general purpose registers, except that loading R0 has no effect (it always stores the value 0x00000000).
Load and Store Instructions All are I-Type
Bit #'s 0 5 6 10 11 15 16 31
Opcode rs1 rd Immediate
Width 6 5 5 16
Data always moved between memory and the register(s) specified by rd
Load and Store Instructions Load/Store Address Calculations:
Load lw rd rs1 imm rd = Mem(Sign_Extend(imm) + rs1)
Store sw rd rs1 imm Mem(Sign_Extend(imm) + rs1) = rd
Load Instructions LB Loads a byte (w/ sign ext.) LBU Loads a byte (w/ zero ext.) LH Loads a halfword (w/ sign ext.) LHU Loads a halfword (w/ zero ext.) LW Loads a word LF Loads a single precision float LD Loads a double precision float*
*to/from a pair of even/odd registers
Store Instructions
SB Stores a byte SH Stores a halfword SW Stores a word SF Stores a single precision float SD Stores a double precision float*
*to/from a pair of even/odd registers
Thank You