Cortex-A8 Technical Reference Manual - ARM Information Center

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16.7 VFP instructions Instruction Cycle Timing All VFP data-processing instructions can execute on the VFP coprocessor. A special subset of the VFP instructions can execute on the NEON Floating-Point (NFP) pipeline. Note This document uses the older assembler language instruction mnemonics. See Appendix B Instruction Mnemonics for information about the Unified Assembler Language (UAL) equivalents of the VFP data-processing instruction mnemonics. See the ARM Architecture Reference Manual for more information on the UAL syntax. 16.7.1 VFP instruction execution in the VFP coprocessor The VFP coprocessor is a nonpipelined floating-point execution engine that can execute any VFPv3 data-processing instruction. Each instruction runs to completion before the next instruction can issue, and there is no forwarding of VFP results to other instructions. Two cycles of decode, stages M2 and M3, are required between consecutive VFP instructions. These decode cycles are included in the cycle timing of this section. The number of cycles required to complete an instruction depends on both the instruction and the input data operands. Floating-point operands can be divided into three broad categories: • normal • subnormal • special. Most numbers are normal and have an internal format that consists of a sign, a fractional number between one and two, and an exponent. Subnormal numbers are too small to represent in the normal space. A subnormal number consists of a sign, a fractional number between zero and one, and a zero in the exponent field. Special numbers are zeros, NaNs, and infinities. Table 16-25 shows the range of cycle times for VFPv3 data-processing instruction with normal numbers. Subnormal numbers usually take more time as the Subnormal penalty column in Table 16-25 shows. Special numbers are handled by separate logic, and usually take less time than what is indicated in this table. Instruction Single precision cycles Table 16-25 VFP Instruction cycle counts Double precision cycles Subnormal penalty FADD 9-10 9-10 operand/result FSUB 9-10 9-10 operand/result FMUL 10-12 11-17 operand/result FNMUL 10-12 11-17 operand/result FMAC 18-21 19-26 operand/intermediate/result FNMAC 18-21 19-26 operand/intermediate/result FMSC 18-21 19-26 operand/intermediate/result FNMSC 18-21 19-26 operand/intermediate/result FDIV 20-37 29-65 operand/result FSQRT 19-33 29-60 operand ARM DDI 0344K Copyright © 2006-2010 ARM Limited. All rights reserved. 16-33 ID060510 Non-Confidential
Instruction Single precision cycles Instruction Cycle Timing Table 16-25 VFP Instruction cycle counts (continued) Double precision cycles FCONST 4 4 none FABS 4 4 none FCPY 4 4 none FNEG 4 4 none FCMP 4 or 7 4 or 7 none FCMPE 4 or 7 4 or 7 none FCMPZ 4 or 7 4 or 7 none FCMPEZ 4 or 7 4 or 7 none FCVTDS 5 - operand FCVTSD - 7 intermediate FSITO 9 9 none FUITO 9 9 none FTOSI 8 8 none FTOUI 8 8 none FTOSIZ 8 8 none FTOUIZ 8 8 none FSHTO 9 9 none FUHTO 9 9 none FSLTO 9 9 none FULTO 9 9 none FTOSH 6 8 none FTOUH 6 8 none FTOSL 6 8 none FTOUL 6 8 none Subnormal penalty The Instruction column of Table 16-25 on page 16-33 indicates the specific VFPv3 data-processing instruction. The Single precision cycles column indicates the number of cycles required for normal single-precision inputs of the associated instruction. The Double precision cycles column indicates the number of cycles required for normal double-precision inputs of the associated instruction. For example, a double-precision FMUL instruction takes any where between 11 and 17 cycles, depending on the data. A single- or double-precision FCMP instruction takes either four or seven cycles, depending on the data. The reason for the wide range of cycles required for normal data is because the VFP coprocessor can detect when a given problem does not require additional computation. For example, if the VFP coprocessor multiplies 3 times 3, the operation takes less time than when it multiplies π times π. ARM DDI 0344K Copyright © 2006-2010 ARM Limited. All rights reserved. 16-34 ID060510 Non-Confidential
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Copyright © 2006-2010 ARM Limited.
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Web Address http://www.arm.com ARM
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Contents 2.14 The program status re
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Contents 16.6 Instruction-specific
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List of Tables Table 3-16 Debug Fea
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List of Tables Table 3-136 Secure o
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List of Tables Table 12-59 Values t
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List of Figures Cortex-A8 Technical
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List of Figures Figure 3-77 BTB arr
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List of Figures Figure 15-16 CTI Ch
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About this manual Product revision
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old Highlights interface elements,
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Feedback Feedback on the product Fe
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1.1 About the processor Introductio
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1.3 Components of the processor L1
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1.3.6 NEON 1.3.7 ETM The NEON unit
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1.5 Debug Introduction The processo
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1.7 Configurable options Table 1-1
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Introduction • The various data a
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1.9.6 r2p0-r2p1 1.9.7 r2p1-r2p2 1.9
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Chapter 2 Programmers Model This ch
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2.2 Thumb-2 instruction set Program
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Bits Field Function Programmers Mod
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2.4 Jazelle Extension 2.4.1 Jazelle
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2.5 Security Extensions architectur
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2.6 Advanced SIMD architecture Prog
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2.8 Processor operating states 2.8.
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2.10 Memory formats 2.10.1 Byte-inv
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2.12 Operating modes Programmers Mo
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System and User r0 r1 r2 r3 r4 r5 r
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2.14 The program status registers 2
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2.14.5 The GE[3:0] bits Programmers
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Mode bits Programmers Model M[4:0]
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2.15 Exceptions 2.15.1 Exception en
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2.15.5 Interrupt request 2.15.6 Abo
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This restores both the PC and the C
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2.15.13 Exception priorities Progra
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2.17 Hardware consideration for Sec
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SECMONOUT[78] instruction caches at
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Chapter 3 System Control Coprocesso
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System Control Coprocessor Register
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3.1.3 MMU control and configuration
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3.2 System control coprocessor regi
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CRn Op1 CRm Op2 Register or operati
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3.2.2 c0, Main ID Register System C
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3.2.4 c0, TCM Type Register 3.2.5 c
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3.2.7 c0, Processor Feature Registe
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• accessible in privileged modes
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System Control Coprocessor Table 3-
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Bits Field Function [11:8] L1 Harva
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Bits Field Function [11:8] Harvard
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31 28 27 24 23 20 19 16 15 12 11 8
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Table 3-30 shows the results of att
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System Control Coprocessor 31 28 27
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Table 3-36 shows the results of att
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• accessible in privileged modes
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CSSR Size 3.2.24 c0, Cache Size Sel
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System Control Coprocessor 31 30 29
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MCR p15, 0, , c1, c0, 0 ; Write Con
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Bits Field [19] Clock stop request
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Bits Field Security State NS S Tabl
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3.2.28 c1, Secure Configuration Reg
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AW EA Function Table 3-55 shows the
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3.2.32 c2, Translation Table Base R
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System Control Coprocessor Figure 3
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Bits Field Function 3.2.35 c5, Data
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3.2.36 c5, Instruction Fault Status
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3.2.38 c6, Data Fault Address Regis
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System Control Coprocessor Note •
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System Control Coprocessor Figure 3
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3.2.41 c8, TLB operations The data
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Figure 3-38 shows the bit arrangeme
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EN b 3.2.44 c9, Count Enable Clear
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EN b 3.2.46 c9, Software Increment
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EN b 3.2.48 c9, Cycle Count Registe
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EN b Table 3-96 shows the results o
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Value Description 0x44 Any cacheabl
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DBGEN || NIDEN 3.2.51 c9, User Enab
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EN 3.2.53 c9, Interrupt Enable Clea
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Figure 3-48 shows the bit arrangeme
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3.2.55 c9, L2 Cache Auxiliary Contr
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Bits Field Function [8:6] Tag RAM l
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TL bit value 3.2.57 c10, TLB preloa
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The PLE Identification and Status R
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3.2.62 c11, PLE enable commands U b
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Bits Field Function System Control
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U bit PLE bit Table 3-129 shows the
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U bit PLE bit System Control Coproc
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3.2.68 c12, Secure or Nonsecure Vec
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3.2.70 c12, Interrupt Status Regist
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The FCSE PID Register is: • a rea
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TLB CAM read/write TLB ATTR read/wr
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MCR p15 0, , c15, c3, 4 ; I-L1 TLB
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31 27 26 22 21 0 Reserved L1 Data 0
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System Control Coprocessor The L1 H
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3.2.78 c15, L1 data array operation
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Instruction L1 Data 0 register Inst
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Parity/ECC RAM read/write Data RAM
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3.2.82 c15, L2 parity/ECC array ope
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3.2.84 c15, L2 data array operation
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4.1 About unaligned and mixed-endia
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Unaligned Data and Mixed-endian Dat
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Chapter 5 Program Flow Prediction T
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5.2 Predicted instructions Program
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Program Flow Prediction Because ret
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5.4 Guidelines for optimal performa
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5.6 Operating system and predictor
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6.1 About the MMU Memory Management
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6.3 16MB supersection support Memor
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6.5 External aborts 6.5.1 External
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6.7 MMU software-accessible registe
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7.1 About the L1 memory system Leve
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7.2.6 Instruction cache maintenance
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L1 inner policy a L2 outer policy N
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7.5 Data cache features 7.5.1 Data
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7.7 Hardware support for virtual al
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Chapter 8 Level 2 Memory System Thi
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8.2 Cache organization 8.2.1 L2 cac
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8.3 Enabling and disabling the L2 c
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Level 2 Memory System Note It is en
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Level 2 Memory System Note You must
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Lock address : LockAddr Lock free :
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8.7 Parity and error correction cod
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9.1 About the external memory inter
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Integer data and CP14 writes Noncac
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9.4 AXI data read/write transaction
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Noncacheable, or strongly ordered,
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Noncacheable store word Noncacheabl
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LA Last Access External Memory Inte
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10.1 Clock domains 10.1.1 AXI clock
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10.2 Reset domains 10.2.1 Power-on
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REFCLK (PLL input) nPORESET ARESETn
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10.3 Power control 10.3.1 Dynamic p
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Clock, Reset, and Power Control the
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ATB APB I/O clamp I/O clamp L/S = L
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ATB APB I/O clamp I/O clamp LS = Le
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Clock, Reset, and Power Control 3.
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Powering up the debug and ETM domai
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7. Perform a normal software reset
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Clock, Reset, and Power Control 5.
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Chapter 11 Design for Test This cha
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In L1 MBIST Instruction Register Fi
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Note Do not test the CAMBIST arrays
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• number of rows of the L2 data,
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Design for Test Not all row setting
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In Design for Test Figure 11-4 show
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Design for Test When testing the ta
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CLK ARESETn MBISTMODE MBISTSHIFT MB
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End-of-test datalog retrieval Desig
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Pattern N RWRXMARCH 8N Row-fast Sta
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4. rscan array, data_seed = invert.
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3. R_, W, R, decr. 4. rscan data fr
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• the data after pass 1 of XADDRB
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(1 + (2 17)) 2 17 = 4,587,520 cycle
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processor input ports WEXTEST WINTE
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Design for Test toggling during shi
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12.1 Debug systems 12.1.1 Debug hos
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12.2.3 Security extensions and debu
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Instruction Mnemonic Description 12
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12.3.6 Power domains and debug 12.3
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Table 12-5 shows the APB interface
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12.4 Debug register descriptions Te
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MRC p14, 0, , c0, c0, 0 ; Read Debu
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31 30 29 28 27 26 25 24 23 22 21 20
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Bits Field Function [21:20] DTR acc
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Bits Field Function To access the D
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12.4.7 Watchpoint Fault Address Reg
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Bits Access Normal address [2] RW V
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12.4.12 Debug Run Control Register
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Table 12-23 shows how the bit value
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BVR[22:20] Meaning b011 The corresp
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Bits Field Function [15:14] Secure
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12.4.18 Operating System Lock Statu
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Debug • The sequence can be aband
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12.5 Management registers Offset Th
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Offset Register number Mnemonic Fun
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Bits Field Function [5] nDMAIRQ nDM
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12.5.7 Claim Tag Clear Register 12.
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12.5.10 Authentication Status Regis
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Table 12-45 shows fields that are i
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12.6 Debug events 12.6.1 Software d
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12.6.5 Watchpoint debug events If a
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Table 12-53 shows the values in the
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12.8 Debug state 12.8.1 Entering de
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12.8.4 Writing to the CPSR in debug
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Mode SCR[0] For CP15 instructions,
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12.8.9 Leaving debug state Imprecis
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12.9.3 Cache usage profiling Debug
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Note DBGPWRDWNREQ must be tied LOW
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If software running on the processo
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Rules for accessing the DCC At the
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} While the processor is running, i
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Debug Table 12-59 Values to write t
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12.11.4 Debug state entry Example 1
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} // Step 1. Update the CPSR value
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Writing the CPSR in debug state Exa
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Debug Example 12-21 Reading a word
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} // Step 9. Check for aborts. abor
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12.12 Debugging systems with energy
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MOV r0, r4 POP {r4, pc} Example 12-
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Chapter 13 NEON and VFP Programmers
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13.2 General-purpose registers 13.2
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13.3 Short vectors 13.3.1 About reg
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13.3.2 Operations using register ba
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NEON and VFP Programmers Model The
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Note All hardware ID information is
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Bits Field Function [12:8] - Reserv
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NEON and VFP Programmers Model Tabl
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13.6 Compliance with the IEEE 754 s
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Underflow NEON and VFP Programmers
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14.1 About the ETM 14.1.1 ETM featu
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14.1.3 NEON Bridge and bus matrix A
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14.3 ETM register summary The ETM r
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Bits Field Function [11:8] Major ET
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14.4.4 Peripheral Identification Re
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See the ETM Architecture Specificat
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Embedded Trace Macrocell Table 14-1
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14.5.3 Enabling events 14.5.4 Addre
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14.7 Context ID tracing Embedded Tr
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14.9 Idle state control Embedded Tr
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Chapter 15 Cross Trigger Interface
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CTICHIN[0] CTICHIN[1] CTICHIN[2] CT
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15.2 Trigger inputs and outputs Tri
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15.3 Connecting asynchronous channe
Page 473 and 474: 15.5 CTI register summary Address o
Page 475 and 476: 15.6 CTI register descriptions This
Page 477 and 478: 15.6.4 CTI Application Trigger Clea
Page 479 and 480: Table 15-10 shows how the bit value
Page 481 and 482: 15.6.12 ASIC Control Register, ASIC
Page 483 and 484: 15.7 CTI Integration Test Registers
Page 485 and 486: 15.7.4 ITTRIGOUTACK, 0xEF0 15.7.5 I
Page 487 and 488: Cross Trigger Interface Table 15-26
Page 489 and 490: 15.8.3 Device Type Identifier, 0xFC
Page 491 and 492: Cross Trigger Interface Table 15-31
Page 493 and 494: 16.1 About instruction cycle timing
Page 495 and 496: Instruction Cycle Timing Example 16
Page 497 and 498: Table 16-4 shows the operation of m
Page 499 and 500: Table 16-9 shows the operation of l
Page 501 and 502: d. See Load/store instructions on p
Page 503 and 504: Instruction Cycle Timing Table 16-1
Page 505 and 506: 16.4 Other pipeline-dependent laten
Page 507 and 508: 16.4.5 Conditional instructions Ins
Page 509 and 510: 16.6 Instruction-specific schedulin
Page 511 and 512: Instruction Cycle Timing VNEG Dd,Dm
Page 513 and 514: VMLA a VMLS a VMLAa VMLSa VQDMLAa V
Page 515 and 516: VSLI VSRI 16.6.5 Advanced SIMD floa
Page 517 and 518: 16.6.6 Advanced SIMD byte permute i
Page 519 and 520: Instruction Table 16-23 shows the o
Page 521 and 522: Instruction VST3 3-reg (unaligned)
Page 523: Instruction VLD3 3-reg (unaligned)
Page 527 and 528: • FMACS, FNMACS • FMSCS, FNMSCS
Page 529 and 530: is dual issued with previous instru
Page 531 and 532: 17.1 About setup and hold times AC
Page 533 and 534: 17.2 AXI interface Table 17-2 shows
Page 535 and 536: 17.3 ATB and CTI interfaces Table 1
Page 537 and 538: AC Characteristics Table 17-4 Timin
Page 539 and 540: 17.6 L2 preload interface AC Charac
Page 541 and 542: 17.8 Miscellaneous signals AC Chara
Page 543 and 544: A.1 AXI interface Signal Descriptio
Page 545 and 546: A.3 MBIST and DFT interface A.3.1 M
Page 547 and 548: A.4 Preload engine interface Table
Page 549 and 550: A.6 Miscellaneous signals Table A-7
Page 551 and 552: Signal I/O Reset Description CFGNMF
Page 553 and 554: Signal I/O Reset Description DBGNOP
Page 555 and 556: Appendix B Instruction Mnemonics Th
Page 557 and 558: Instruction Mnemonics Table B-1 Adv
Page 559 and 560: Appendix C Revisions This appendix
Page 561 and 562: Revisions Added text to clarify des
Page 563 and 564: Glossary This glossary describes so
Page 565 and 566: Glossary Automatic Test Pattern Gen
Page 567 and 568: Big-endian memory Memory in which:
Page 569 and 570: Conditional execution Glossary incl
Page 571 and 572: Glossary Embedded Trace Macrocell (
Page 573 and 574: Illegal instruction An instruction
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Glossary NaN Not a number. A symbol
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Glossary Significand The component
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Glossary Watchpoint A watchpoint is
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