476 lines
26 KiB
XML
476 lines
26 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<?xml-stylesheet type="text/xsl" encoding="UTF-8" href="iform.xsl" version="1.0"?>
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<!DOCTYPE instructionsection PUBLIC "-//ARM//DTD instructionsection //EN" "iform-p.dtd">
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<!-- Copyright (c) 2010-2022 Arm Limited or its affiliates. All rights reserved. -->
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<!-- This document is Non-Confidential. This document may only be used and distributed in accordance with the terms of the agreement entered into by Arm and the party that Arm delivered this document to. -->
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<instructionsection id="LDRSB_i" title="LDRSB (immediate) -- AArch32" type="instruction">
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<docvars>
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<docvar key="instr-class" value="general" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<heading>LDRSB (immediate)</heading>
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<desc>
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<brief>
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<para>Load Register Signed Byte (immediate)</para>
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</brief>
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<authored>
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<para>Load Register Signed Byte (immediate) calculates an address from a base register value and an immediate offset, loads a byte from memory, sign-extends it to form a 32-bit word, and writes it to a register. It can use offset, post-indexed, or pre-indexed addressing. For information about memory accesses see <xref linkend="Chddjfjf">Memory accesses</xref>.</para>
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</authored>
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<encodingnotes>
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<para>For more information about the <arm-defined-word>constrained unpredictable</arm-defined-word> behavior of this instruction, see <xref linkend="CJAEGDJC">Architectural Constraints on UNPREDICTABLE behaviors</xref>.</para>
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</encodingnotes>
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</desc>
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<operationalnotes>
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<para>If CPSR.DIT is 1, the timing of this instruction is insensitive to the value of the data being loaded or stored.</para>
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</operationalnotes>
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<alias_list howmany="0"></alias_list>
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<classes>
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<classesintro count="3">
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<txt>It has encodings from the following instruction sets:</txt>
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<txt> A32 (</txt>
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<a href="#iclass_a1">A1</a>
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<txt>)</txt>
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<txt> and </txt>
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<txt> T32 (</txt>
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<a href="#iclass_t1">T1</a>
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<txt> and </txt>
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<a href="#iclass_t2">T2</a>
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<txt>)</txt>
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<txt>.</txt>
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</classesintro>
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<iclass name="A1" oneof="3" id="iclass_a1" no_encodings="3" isa="A32">
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<docvars>
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<docvar key="armarmheading" value="A1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="A32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<iclassintro count="3"></iclassintro>
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<regdiagram form="32" psname="aarch32/instrs/LDRSB_i/A1_A.txt" tworows="1">
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<box hibit="31" width="4" name="cond" usename="1" settings="4" constraint="!= 1111">
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<c colspan="4">!= 1111</c>
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</box>
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<box hibit="27" width="3" settings="3">
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<c>0</c>
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="24" name="P" usename="1">
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<c></c>
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</box>
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<box hibit="23" name="U" usename="1">
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<c></c>
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</box>
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<box hibit="22" settings="1">
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<c>1</c>
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</box>
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<box hibit="21" name="W" usename="1">
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<c></c>
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</box>
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<box hibit="20" name="o1" settings="1">
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<c>1</c>
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</box>
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<box hibit="19" width="4" name="Rn" usename="1" settings="4" constraint="!= 1111">
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<c colspan="4">!= 1111</c>
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</box>
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<box hibit="15" width="4" name="Rt" usename="1">
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<c colspan="4"></c>
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</box>
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<box hibit="11" width="4" name="imm4H" usename="1">
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<c colspan="4"></c>
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</box>
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<box hibit="7" settings="1">
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<c>1</c>
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</box>
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<box hibit="6" width="2" name="op2" settings="2">
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<c>1</c>
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<c>0</c>
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</box>
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<box hibit="4" settings="1">
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<c>1</c>
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</box>
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<box hibit="3" width="4" name="imm4L" usename="1">
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<c colspan="4"></c>
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</box>
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</regdiagram>
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<encoding name="LDRSB_i_A1_off" oneofinclass="3" oneof="7" label="Offset" bitdiffs="P == 1 && W == 0">
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<docvars>
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<docvar key="address-form" value="base-plus-offset" />
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<docvar key="address-offset" value="signed-offset" />
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<docvar key="armarmheading" value="A1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="A32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<box hibit="24" width="1" name="P">
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<c>1</c>
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</box>
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<box hibit="21" width="1" name="W">
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<c>0</c>
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</box>
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<asmtemplate><text>LDRSB</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text><text> </text><a link="sa_rt" hover="General-purpose register to be transferred (field "Rt")"><Rt></a><text>, [</text><a link="sa_rn" hover="General-purpose base register (field "Rn")"><Rn></a><text> </text><text>{</text><text>, #</text><a link="sa__plusminus_" hover="Specifies the offset is added to or subtracted from the base register (field "U") [+,-]">{+/-}</a><a link="sa_imm_2" hover="8-bit unsigned immediate byte offset [0-255] (field "imm4H:imm4L")"><imm></a><text>}</text><text>]</text></asmtemplate>
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</encoding>
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<encoding name="LDRSB_i_A1_post" oneofinclass="3" oneof="7" label="Post-indexed" bitdiffs="P == 0 && W == 0">
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<docvars>
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<docvar key="address-form" value="post-indexed" />
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<docvar key="armarmheading" value="A1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="A32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<box hibit="24" width="1" name="P">
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<c>0</c>
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</box>
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<box hibit="21" width="1" name="W">
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<c>0</c>
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</box>
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<asmtemplate><text>LDRSB</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text><text> </text><a link="sa_rt" hover="General-purpose register to be transferred (field "Rt")"><Rt></a><text>, [</text><a link="sa_rn" hover="General-purpose base register (field "Rn")"><Rn></a><text>], #</text><a link="sa__plusminus_" hover="Specifies the offset is added to or subtracted from the base register (field "U") [+,-]">{+/-}</a><a link="sa_imm_2" hover="8-bit unsigned immediate byte offset [0-255] (field "imm4H:imm4L")"><imm></a></asmtemplate>
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</encoding>
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<encoding name="LDRSB_i_A1_pre" oneofinclass="3" oneof="7" label="Pre-indexed" bitdiffs="P == 1 && W == 1">
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<docvars>
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<docvar key="address-form" value="pre-indexed" />
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<docvar key="armarmheading" value="A1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="A32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<box hibit="24" width="1" name="P">
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<c>1</c>
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</box>
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<box hibit="21" width="1" name="W">
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<c>1</c>
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</box>
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<asmtemplate><text>LDRSB</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text><text> </text><a link="sa_rt" hover="General-purpose register to be transferred (field "Rt")"><Rt></a><text>, [</text><a link="sa_rn" hover="General-purpose base register (field "Rn")"><Rn></a><text>, #</text><a link="sa__plusminus_" hover="Specifies the offset is added to or subtracted from the base register (field "U") [+,-]">{+/-}</a><a link="sa_imm_2" hover="8-bit unsigned immediate byte offset [0-255] (field "imm4H:imm4L")"><imm></a><text>]!</text></asmtemplate>
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</encoding>
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<ps_section howmany="1">
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<ps name="aarch32/instrs/LDRSB_i/A1_A.txt" mylink="aarch32.instrs.LDRSB_i.A1_A.txt" enclabels="" sections="1" secttype="noheading">
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<pstext mayhavelinks="1" section="Decode" rep_section="decode">if Rn == '1111' then SEE "LDRSB (literal)";
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if P == '0' && W == '1' then SEE "LDRSBT";
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t = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rt); n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn); imm32 = <a link="impl-shared.ZeroExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) ZeroExtend(bits(M) x, integer N)">ZeroExtend</a>(imm4H:imm4L, 32);
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index = (P == '1'); add = (U == '1'); wback = (P == '0') || (W == '1');
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if t == 15 || (wback && n == t) then UNPREDICTABLE;</pstext>
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</ps>
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</ps_section>
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<constrained_unpredictables encoding="A1" ps_block="Decode">
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<cu_case>
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<cu_cause>
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<pstext mayhavelinks="1">wback && n == t</pstext>
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</cu_cause>
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<cu_type constraint="Constraint_UNDEF" />
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<cu_type constraint="Constraint_NOP" />
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<cu_type>
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<cu_type_text>The instruction performs all of the loads using the specified addressing mode and the content of the register that is written back is UNKNOWN. In addition, if an exception occurs during such an instruction, the base address might be corrupted so that the instruction cannot be repeated.</cu_type_text>
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</cu_type>
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</cu_case>
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</constrained_unpredictables>
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</iclass>
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<iclass name="T1" oneof="3" id="iclass_t1" no_encodings="1" isa="T32">
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<docvars>
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<docvar key="address-form" value="base-plus-offset" />
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<docvar key="armarmheading" value="T1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<iclassintro count="1"></iclassintro>
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<regdiagram form="16x2" psname="aarch32/instrs/LDRSB_i/T1_A.txt" tworows="1">
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<box hibit="31" width="9" settings="9">
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>0</c>
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<c>0</c>
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<c>1</c>
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<c>1</c>
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</box>
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<box hibit="22" width="2" name="size" settings="2">
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="20" settings="1">
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<c>1</c>
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</box>
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<box hibit="19" width="4" name="Rn" usename="1" settings="4" constraint="!= 1111">
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<c colspan="4">!= 1111</c>
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</box>
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<box hibit="15" width="4" name="Rt" usename="1" settings="4" constraint="!= 1111">
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<c colspan="4">!= 1111</c>
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</box>
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<box hibit="11" width="12" name="imm12" usename="1">
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<c colspan="12"></c>
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</box>
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</regdiagram>
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<encoding name="LDRSB_i_T1" oneofinclass="1" oneof="7" label="T1">
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<docvars>
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<docvar key="address-form" value="base-plus-offset" />
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<docvar key="armarmheading" value="T1" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<asmtemplate><text>LDRSB</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text><text> </text><a link="sa_rt" hover="General-purpose register to be transferred (field "Rt")"><Rt></a><text>, [</text><a link="sa_rn" hover="General-purpose base register (field "Rn")"><Rn></a><text> </text><text>{</text><text>, #</text><a link="sa__plus_" hover="Specifies the offset is added to the base register">{+}</a><a link="sa_imm" hover="Optional 12-bit unsigned immediate byte offset [0-4095], default 0 (field "imm12")"><imm></a><text>}</text><text>]</text></asmtemplate>
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</encoding>
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<ps_section howmany="1">
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<ps name="aarch32/instrs/LDRSB_i/T1_A.txt" mylink="aarch32.instrs.LDRSB_i.T1_A.txt" enclabels="" sections="1" secttype="noheading">
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<pstext mayhavelinks="1" section="Decode" rep_section="decode">if Rt == '1111' then SEE "PLI";
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if Rn == '1111' then SEE "LDRSB (literal)";
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t = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rt); n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn); imm32 = <a link="impl-shared.ZeroExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) ZeroExtend(bits(M) x, integer N)">ZeroExtend</a>(imm12, 32);
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index = TRUE; add = TRUE; wback = FALSE;
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// Armv8-A removes UNPREDICTABLE for R13</pstext>
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</ps>
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</ps_section>
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</iclass>
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<iclass name="T2" oneof="3" id="iclass_t2" no_encodings="3" isa="T32">
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<docvars>
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<docvar key="armarmheading" value="T2" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<iclassintro count="3"></iclassintro>
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<regdiagram form="16x2" psname="aarch32/instrs/LDRSB_i/T2_A.txt" tworows="1">
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<box hibit="31" width="9" settings="9">
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>1</c>
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<c>0</c>
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<c>0</c>
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<c>1</c>
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<c>0</c>
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</box>
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<box hibit="22" width="2" name="size" settings="2">
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<c>0</c>
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<c>0</c>
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</box>
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<box hibit="20" settings="1">
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<c>1</c>
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</box>
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<box hibit="19" width="4" name="Rn" usename="1" settings="4" constraint="!= 1111">
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<c colspan="4">!= 1111</c>
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</box>
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<box hibit="15" width="4" name="Rt" usename="1">
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<c colspan="4"></c>
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</box>
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<box hibit="11" settings="1">
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<c>1</c>
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</box>
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<box hibit="10" name="P" usename="1">
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<c></c>
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</box>
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<box hibit="9" name="U" usename="1">
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<c></c>
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</box>
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<box hibit="8" name="W" usename="1">
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<c></c>
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</box>
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<box hibit="7" width="8" name="imm8" usename="1">
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<c colspan="8"></c>
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</box>
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</regdiagram>
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<encoding name="LDRSB_i_T2_off" oneofinclass="3" oneof="7" label="Offset" bitdiffs="Rt != 1111 && P == 1 && U == 0 && W == 0">
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<docvars>
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<docvar key="address-form" value="base-plus-offset" />
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<docvar key="armarmheading" value="T2" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<box hibit="15" width="4" name="Rt">
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<c>N</c>
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<c>N</c>
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<c>N</c>
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<c>N</c>
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</box>
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<box hibit="10" width="1" name="P">
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<c>1</c>
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</box>
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<box hibit="9" width="1" name="U">
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<c>0</c>
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</box>
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<box hibit="8" width="1" name="W">
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<c>0</c>
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</box>
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<asmtemplate><text>LDRSB</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text><text> </text><a link="sa_rt" hover="General-purpose register to be transferred (field "Rt")"><Rt></a><text>, [</text><a link="sa_rn" hover="General-purpose base register (field "Rn")"><Rn></a><text> </text><text>{</text><text>, #-</text><a link="sa_imm_1" hover="8-bit unsigned immediate byte offset [0-255] (field "imm8")"><imm></a><text>}</text><text>]</text></asmtemplate>
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</encoding>
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<encoding name="LDRSB_i_T2_post" oneofinclass="3" oneof="7" label="Post-indexed" bitdiffs="P == 0 && W == 1">
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<docvars>
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<docvar key="address-form" value="post-indexed" />
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<docvar key="armarmheading" value="T2" />
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<docvar key="instr-class" value="general" />
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<docvar key="isa" value="T32" />
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<docvar key="mnemonic" value="LDRSB" />
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</docvars>
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<box hibit="10" width="1" name="P">
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<c>0</c>
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</box>
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<box hibit="8" width="1" name="W">
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<c>1</c>
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</box>
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<asmtemplate><text>LDRSB</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text><text> </text><a link="sa_rt" hover="General-purpose register to be transferred (field "Rt")"><Rt></a><text>, [</text><a link="sa_rn" hover="General-purpose base register (field "Rn")"><Rn></a><text>], #</text><a link="sa__plusminus_" hover="Specifies the offset is added to or subtracted from the base register (field "U") [+,-]">{+/-}</a><a link="sa_imm_1" hover="8-bit unsigned immediate byte offset [0-255] (field "imm8")"><imm></a></asmtemplate>
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</encoding>
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<encoding name="LDRSB_i_T2_pre" oneofinclass="3" oneof="7" label="Pre-indexed" bitdiffs="P == 1 && W == 1">
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<docvars>
|
|
<docvar key="address-form" value="pre-indexed" />
|
|
<docvar key="armarmheading" value="T2" />
|
|
<docvar key="instr-class" value="general" />
|
|
<docvar key="isa" value="T32" />
|
|
<docvar key="mnemonic" value="LDRSB" />
|
|
</docvars>
|
|
<box hibit="10" width="1" name="P">
|
|
<c>1</c>
|
|
</box>
|
|
<box hibit="8" width="1" name="W">
|
|
<c>1</c>
|
|
</box>
|
|
<asmtemplate><text>LDRSB</text><text>{</text><a link="sa_c" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><c></a><text>}</text><text>{</text><a link="sa_q" hover="See {xref{ARMARM_Babbefhf}{Standard assembler syntax fields}}"><q></a><text>}</text><text> </text><a link="sa_rt" hover="General-purpose register to be transferred (field "Rt")"><Rt></a><text>, [</text><a link="sa_rn" hover="General-purpose base register (field "Rn")"><Rn></a><text>, #</text><a link="sa__plusminus_" hover="Specifies the offset is added to or subtracted from the base register (field "U") [+,-]">{+/-}</a><a link="sa_imm_1" hover="8-bit unsigned immediate byte offset [0-255] (field "imm8")"><imm></a><text>]!</text></asmtemplate>
|
|
</encoding>
|
|
<ps_section howmany="1">
|
|
<ps name="aarch32/instrs/LDRSB_i/T2_A.txt" mylink="aarch32.instrs.LDRSB_i.T2_A.txt" enclabels="" sections="1" secttype="noheading">
|
|
<pstext mayhavelinks="1" section="Decode" rep_section="decode">if Rt == '1111' && P == '1' && U == '0' && W == '0' then SEE "PLI";
|
|
if Rn == '1111' then SEE "LDRSB (literal)";
|
|
if P == '1' && U == '1' && W == '0' then SEE "LDRSBT";
|
|
if P == '0' && W == '0' then UNDEFINED;
|
|
t = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rt); n = <a link="impl-shared.UInt.1" file="shared_pseudocode.xml" hover="function: integer UInt(bits(N) x)">UInt</a>(Rn); imm32 = <a link="impl-shared.ZeroExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) ZeroExtend(bits(M) x, integer N)">ZeroExtend</a>(imm8, 32);
|
|
index = (P == '1'); add = (U == '1'); wback = (W == '1');
|
|
if (t == 15 && W == '1') || (wback && n == t) then UNPREDICTABLE;
|
|
// Armv8-A removes UNPREDICTABLE for R13</pstext>
|
|
</ps>
|
|
</ps_section>
|
|
<constrained_unpredictables encoding="T2" ps_block="Decode">
|
|
<cu_case>
|
|
<cu_cause>
|
|
<pstext mayhavelinks="1">wback && n == t</pstext>
|
|
</cu_cause>
|
|
<cu_type constraint="Constraint_UNDEF" />
|
|
<cu_type constraint="Constraint_NOP" />
|
|
<cu_type>
|
|
<cu_type_text>The instruction performs all of the loads using the specified addressing mode and the content of the register that is written back is UNKNOWN. In addition, if an exception occurs during such an instruction, the base address might be corrupted so that the instruction cannot be repeated.</cu_type_text>
|
|
</cu_type>
|
|
</cu_case>
|
|
</constrained_unpredictables>
|
|
</iclass>
|
|
</classes>
|
|
<explanations scope="all">
|
|
<explanation enclist="LDRSB_i_A1_off, LDRSB_i_T1, LDRSB_i_T2_pre" symboldefcount="1">
|
|
<symbol link="sa_c"><c></symbol>
|
|
<account encodedin="">
|
|
<intro>
|
|
<para>See <xref linkend="Babbefhf">Standard assembler syntax fields</xref>.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_A1_off, LDRSB_i_T1, LDRSB_i_T2_pre" symboldefcount="1">
|
|
<symbol link="sa_q"><q></symbol>
|
|
<account encodedin="">
|
|
<intro>
|
|
<para>See <xref linkend="Babbefhf">Standard assembler syntax fields</xref>.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_A1_off, LDRSB_i_T1, LDRSB_i_T2_pre" symboldefcount="1">
|
|
<symbol link="sa_rt"><Rt></symbol>
|
|
<account encodedin="Rt">
|
|
<intro>
|
|
<para>Is the general-purpose register to be transferred, encoded in the "Rt" field.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_A1_off, LDRSB_i_T1, LDRSB_i_T2_pre" symboldefcount="1">
|
|
<symbol link="sa_rn"><Rn></symbol>
|
|
<account encodedin="Rn">
|
|
<intro>
|
|
<para>Is the general-purpose base register, encoded in the "Rn" field. For PC use see <xref linkend="A32T32-base.instructions.LDRSB_l">LDRSB (literal)</xref>.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_A1_off, LDRSB_i_T2_pre" symboldefcount="1">
|
|
<symbol link="sa__plusminus_">+/-</symbol>
|
|
<definition encodedin="U">
|
|
<intro>Specifies the offset is added to or subtracted from the base register, defaulting to + if omitted and </intro>
|
|
<table class="valuetable">
|
|
<tgroup cols="2">
|
|
<thead>
|
|
<row>
|
|
<entry class="bitfield">U</entry>
|
|
<entry class="symbol">+/-</entry>
|
|
</row>
|
|
</thead>
|
|
<tbody>
|
|
<row>
|
|
<entry class="bitfield">0</entry>
|
|
<entry class="symbol">-</entry>
|
|
</row>
|
|
<row>
|
|
<entry class="bitfield">1</entry>
|
|
<entry class="symbol">+</entry>
|
|
</row>
|
|
</tbody>
|
|
</tgroup>
|
|
</table>
|
|
</definition>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_T1" symboldefcount="1">
|
|
<symbol link="sa__plus_">+</symbol>
|
|
<account encodedin="">
|
|
<intro>
|
|
<para>Specifies the offset is added to the base register.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_A1_off" symboldefcount="1">
|
|
<symbol link="sa_imm_2"><imm></symbol>
|
|
<account encodedin="imm4H:imm4L">
|
|
<docvars>
|
|
<docvar key="address-form" value="base-plus-offset" />
|
|
<docvar key="address-offset" value="signed-offset" />
|
|
<docvar key="armarmheading" value="A1" />
|
|
<docvar key="isa" value="A32" />
|
|
</docvars>
|
|
<intro>
|
|
<para>For encoding A1: is the 8-bit unsigned immediate byte offset, in the range 0 to 255, defaulting to 0 if omitted, and encoded in the "imm4H:imm4L" field.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_T1" symboldefcount="2">
|
|
<symbol link="sa_imm"><imm></symbol>
|
|
<account encodedin="imm12">
|
|
<docvars>
|
|
<docvar key="address-form" value="base-plus-offset" />
|
|
<docvar key="armarmheading" value="T1" />
|
|
<docvar key="isa" value="T32" />
|
|
</docvars>
|
|
<intro>
|
|
<para>For encoding T1: is an optional 12-bit unsigned immediate byte offset, in the range 0 to 4095, defaulting to 0 and encoded in the "imm12" field.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
<explanation enclist="LDRSB_i_T2_pre" symboldefcount="3">
|
|
<symbol link="sa_imm_1"><imm></symbol>
|
|
<account encodedin="imm8">
|
|
<docvars>
|
|
<docvar key="address-form" value="pre-indexed" />
|
|
<docvar key="armarmheading" value="T2" />
|
|
<docvar key="isa" value="T32" />
|
|
</docvars>
|
|
<intro>
|
|
<para>For encoding T2: is an 8-bit unsigned immediate byte offset, in the range 0 to 255, defaulting to 0 if omitted, and encoded in the "imm8" field.</para>
|
|
</intro>
|
|
</account>
|
|
</explanation>
|
|
</explanations>
|
|
<ps_section howmany="1">
|
|
<ps name="aarch32/instrs/LDRSB_i/Op_A.txt" mylink="execute" enclabels="" sections="1" secttype="Operation">
|
|
<pstext mayhavelinks="1" section="Execute" rep_section="execute">if <a link="impl-aarch32.ConditionPassed.0" file="shared_pseudocode.xml" hover="function: boolean ConditionPassed()">ConditionPassed</a>() then
|
|
EncodingSpecificOperations();
|
|
offset_addr = if add then (<a link="impl-aarch32.R.read.1" file="shared_pseudocode.xml" hover="accessor: bits(32) R[integer n]">R</a>[n] + imm32) else (<a link="impl-aarch32.R.read.1" file="shared_pseudocode.xml" hover="accessor: bits(32) R[integer n]">R</a>[n] - imm32);
|
|
address = if index then offset_addr else <a link="impl-aarch32.R.read.1" file="shared_pseudocode.xml" hover="accessor: bits(32) R[integer n]">R</a>[n];
|
|
<a link="impl-aarch32.R.write.1" file="shared_pseudocode.xml" hover="accessor: R[integer n] = bits(32) value">R</a>[t] = <a link="impl-shared.SignExtend.2" file="shared_pseudocode.xml" hover="function: bits(N) SignExtend(bits(M) x, integer N)">SignExtend</a>(<a link="impl-aarch32.MemU.read.2" file="shared_pseudocode.xml" hover="accessor: bits(8*size) MemU[bits(32) address, integer size]">MemU</a>[address,1], 32);
|
|
if wback then <a link="impl-aarch32.R.write.1" file="shared_pseudocode.xml" hover="accessor: R[integer n] = bits(32) value">R</a>[n] = offset_addr;</pstext>
|
|
</ps>
|
|
</ps_section>
|
|
</instructionsection>
|