Cortex-A8 Technical Reference Manual - ARM Information Center

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Chapter 4 Unaligned Data and Mixed-endian Data Support This chapter describes the unaligned and mixed-endianness data access support for the processor. It contains the following sections: • About unaligned and mixed-endian data on page 4-2 • Unaligned data access support on page 4-3 • Mixed-endian access support on page 4-5. ARM DDI 0344K Copyright © 2006-2010 ARM Limited. All rights reserved. 4-1 ID060510 Non-Confidential
4.1 About unaligned and mixed-endian data Unaligned Data and Mixed-endian Data Support The processor has the following features to support unaligned and mixed-endian data access: • permanently enabled support for unaligned data access • architecturally defined unaligned word, unaligned halfword, and word-aligned doubleword access • byte-reverse instructions that operate on general-purpose register contents to support signed and unsigned halfword data values • separate endianness control for data with instructions fixed as little-endian format, naturally aligned, but with legacy support for 32-bit word-invariant binary images and ROM • EE bit in CP15 c1 Control Register 1 that controls load and store endianness during exceptions • ARM and Thumb instructions to change the endianness and the E flag in the Program Status Registers (PSRs) • byte-invariant addressing to support fine-grain big-endian and little-endian shared data structures, to conform to a shared memory standard. Note Instructions are always little-endian and must be aligned according to the size of the instruction: • 32-bit ARM instructions must be word-aligned with address bits [1:0] equal to b00. • 16-bit or 32-bit Thumb instructions must be halfword-aligned with address bit [0] equal to 0. ARM DDI 0344K Copyright © 2006-2010 ARM Limited. All rights reserved. 4-2 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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Page 177 and 178: TL bit value 3.2.57 c10, TLB preloa
Page 179 and 180: System Control Coprocessor Table 3-
Page 183 and 184: The PLE Identification and Status R
Page 187 and 188: 3.2.62 c11, PLE enable commands U b
Page 189 and 190: Bits Field Function System Control
Page 191 and 192: U bit PLE bit Table 3-129 shows the
Page 193 and 194: U bit PLE bit System Control Coproc
Page 195 and 196: 3.2.68 c12, Secure or Nonsecure Vec
Page 197 and 198: 3.2.70 c12, Interrupt Status Regist
Page 199 and 200: The FCSE PID Register is: • a rea
Page 203 and 204: TLB CAM read/write TLB ATTR read/wr
Page 205 and 206: MCR p15 0, , c15, c3, 4 ; I-L1 TLB
Page 207 and 208: 31 27 26 22 21 0 Reserved L1 Data 0
Page 209 and 210: System Control Coprocessor The L1 H
Page 211 and 212: 3.2.78 c15, L1 data array operation
Page 213 and 214: Instruction L1 Data 0 register Inst
Page 215 and 216: Parity/ECC RAM read/write Data RAM
Page 217 and 218: 3.2.82 c15, L2 parity/ECC array ope
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Page 223 and 224: Unaligned Data and Mixed-endian Dat
Page 225 and 226: Chapter 5 Program Flow Prediction T
Page 227 and 228: 5.2 Predicted instructions Program
Page 229 and 230: Program Flow Prediction Because ret
Page 231 and 232: 5.4 Guidelines for optimal performa
Page 233 and 234: 5.6 Operating system and predictor
Page 235 and 236: 6.1 About the MMU Memory Management
Page 237 and 238: 6.3 16MB supersection support Memor
Page 239 and 240: 6.5 External aborts 6.5.1 External
Page 241 and 242: 6.7 MMU software-accessible registe
Page 243 and 244: 7.1 About the L1 memory system Leve
Page 245 and 246: 7.2.6 Instruction cache maintenance
Page 247 and 248: L1 inner policy a L2 outer policy N
Page 249 and 250: 7.5 Data cache features 7.5.1 Data
Page 251 and 252: 7.7 Hardware support for virtual al
Page 253 and 254: Chapter 8 Level 2 Memory System Thi
Page 255 and 256: 8.2 Cache organization 8.2.1 L2 cac
Page 257 and 258: 8.3 Enabling and disabling the L2 c
Page 259 and 260: Level 2 Memory System Note It is en
Page 261 and 262: Level 2 Memory System Note You must
Page 263 and 264: Lock address : LockAddr Lock free :
Page 265 and 266: 8.7 Parity and error correction cod
Page 267 and 268: 9.1 About the external memory inter
Page 269 and 270: 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
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15.5 CTI register summary Address o
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15.6 CTI register descriptions This
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15.6.4 CTI Application Trigger Clea
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Table 15-10 shows how the bit value
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15.6.12 ASIC Control Register, ASIC
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15.7 CTI Integration Test Registers
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15.7.4 ITTRIGOUTACK, 0xEF0 15.7.5 I
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Cross Trigger Interface Table 15-26
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15.8.3 Device Type Identifier, 0xFC
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Cross Trigger Interface Table 15-31
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16.1 About instruction cycle timing
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Instruction Cycle Timing Example 16
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Table 16-4 shows the operation of m
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Table 16-9 shows the operation of l
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d. See Load/store instructions on p
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Instruction Cycle Timing Table 16-1
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16.4 Other pipeline-dependent laten
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16.4.5 Conditional instructions Ins
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16.6 Instruction-specific schedulin
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Instruction Cycle Timing VNEG Dd,Dm
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VMLA a VMLS a VMLAa VMLSa VQDMLAa V
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VSLI VSRI 16.6.5 Advanced SIMD floa
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16.6.6 Advanced SIMD byte permute i
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Instruction Table 16-23 shows the o
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Instruction VST3 3-reg (unaligned)
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Instruction VLD3 3-reg (unaligned)
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Instruction Single precision cycles
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• FMACS, FNMACS • FMSCS, FNMSCS
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is dual issued with previous instru
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17.1 About setup and hold times AC
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17.2 AXI interface Table 17-2 shows
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17.3 ATB and CTI interfaces Table 1
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AC Characteristics Table 17-4 Timin
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17.6 L2 preload interface AC Charac
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17.8 Miscellaneous signals AC Chara
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A.1 AXI interface Signal Descriptio
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A.3 MBIST and DFT interface A.3.1 M
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A.4 Preload engine interface Table
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A.6 Miscellaneous signals Table A-7
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Signal I/O Reset Description CFGNMF
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Signal I/O Reset Description DBGNOP
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Appendix B Instruction Mnemonics Th
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Instruction Mnemonics Table B-1 Adv
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Appendix C Revisions This appendix
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Revisions Added text to clarify des
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Glossary This glossary describes so
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Glossary Automatic Test Pattern Gen
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Big-endian memory Memory in which:
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Conditional execution Glossary incl
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Glossary Embedded Trace Macrocell (
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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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