qemu/target/arm/t16.decode

# Thumb1 instructions
#
#  Copyright (c) 2019 Linaro, Ltd
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, see <http://www.gnu.org/licenses/>.

#
# This file is processed by scripts/decodetree.py
#

&empty           !extern
&s_rrr_shi       !extern s rd rn rm shim shty
&s_rrr_shr       !extern s rn rd rm rs shty
&s_rri_rot       !extern s rn rd imm rot
&s_rrrr          !extern s rd rn rm ra
&rrr_rot         !extern rd rn rm rot
&rr              !extern rd rm
&ri              !extern rd imm
&r               !extern rm
&i               !extern imm
&ldst_rr         !extern p w u rn rt rm shimm shtype
&ldst_ri         !extern p w u rn rt imm
&ldst_block      !extern rn i b u w list
&setend          !extern E
&cps             !extern mode imod M A I F
&ci              !extern cond imm

# Set S if the instruction is outside of an IT block.
%s               !function=t16_setflags

# Data-processing (two low registers)

%reg_0           0:3

@lll_noshr       ...... .... rm:3 rd:3 \
                 &s_rrr_shi %s rn=%reg_0 shim=0 shty=0
@xll_noshr       ...... .... rm:3 rn:3 \
                 &s_rrr_shi s=1 rd=0 shim=0 shty=0
@lxl_shr         ...... .... rs:3 rd:3 \
                 &s_rrr_shr %s rm=%reg_0 rn=0

AND_rrri         010000 0000 ... ...            @lll_noshr
EOR_rrri         010000 0001 ... ...            @lll_noshr
MOV_rxrr         010000 0010 ... ...            @lxl_shr shty=0  # LSL
MOV_rxrr         010000 0011 ... ...            @lxl_shr shty=1  # LSR
MOV_rxrr         010000 0100 ... ...            @lxl_shr shty=2  # ASR
ADC_rrri         010000 0101 ... ...            @lll_noshr
SBC_rrri         010000 0110 ... ...            @lll_noshr
MOV_rxrr         010000 0111 ... ...            @lxl_shr shty=3  # ROR
TST_xrri         010000 1000 ... ...            @xll_noshr
RSB_rri          010000 1001 rn:3 rd:3          &s_rri_rot %s imm=0 rot=0
CMP_xrri         010000 1010 ... ...            @xll_noshr
CMN_xrri         010000 1011 ... ...            @xll_noshr
ORR_rrri         010000 1100 ... ...            @lll_noshr
MUL              010000 1101 rn:3 rd:3          &s_rrrr %s rm=%reg_0 ra=0
BIC_rrri         010000 1110 ... ...            @lll_noshr
MVN_rxri         010000 1111 ... ...            @lll_noshr

# Load/store (register offset)

@ldst_rr         ....... rm:3 rn:3 rt:3 \
                 &ldst_rr p=1 w=0 u=1 shimm=0 shtype=0

STR_rr           0101 000 ... ... ...           @ldst_rr
STRH_rr          0101 001 ... ... ...           @ldst_rr
STRB_rr          0101 010 ... ... ...           @ldst_rr
LDRSB_rr         0101 011 ... ... ...           @ldst_rr
LDR_rr           0101 100 ... ... ...           @ldst_rr
LDRH_rr          0101 101 ... ... ...           @ldst_rr
LDRB_rr          0101 110 ... ... ...           @ldst_rr
LDRSH_rr         0101 111 ... ... ...           @ldst_rr

# Load/store word/byte (immediate offset)

%imm5_6x4       6:5 !function=times_4

@ldst_ri_1      ..... imm:5 rn:3 rt:3 \
                &ldst_ri p=1 w=0 u=1
@ldst_ri_4      ..... ..... rn:3 rt:3 \
                &ldst_ri p=1 w=0 u=1 imm=%imm5_6x4

STR_ri          01100 ..... ... ...             @ldst_ri_4
LDR_ri          01101 ..... ... ...             @ldst_ri_4
STRB_ri         01110 ..... ... ...             @ldst_ri_1
LDRB_ri         01111 ..... ... ...             @ldst_ri_1

# Load/store halfword (immediate offset)

%imm5_6x2       6:5 !function=times_2
@ldst_ri_2      ..... ..... rn:3 rt:3 \
                &ldst_ri p=1 w=0 u=1 imm=%imm5_6x2

STRH_ri         10000 ..... ... ...             @ldst_ri_2
LDRH_ri         10001 ..... ... ...             @ldst_ri_2

# Load/store (SP-relative)

%imm8_0x4       0:8 !function=times_4
@ldst_spec_i    ..... rt:3 ........ \
                &ldst_ri p=1 w=0 u=1 imm=%imm8_0x4

STR_ri          10010 ... ........              @ldst_spec_i rn=13
LDR_ri          10011 ... ........              @ldst_spec_i rn=13

# Load (PC-relative)

LDR_ri          01001 ... ........              @ldst_spec_i rn=15

# Add PC/SP (immediate)

ADR             10100 rd:3 ........             imm=%imm8_0x4
ADD_rri         10101 rd:3 ........ \
                &s_rri_rot rn=13 s=0 rot=0 imm=%imm8_0x4  # SP

# Load/store multiple

@ldstm          ..... rn:3 list:8               &ldst_block i=1 b=0 u=0 w=1

STM             11000 ... ........              @ldstm
LDM_t16         11001 ... ........              @ldstm

# Shift (immediate)

@shift_i        ..... shim:5 rm:3 rd:3          &s_rrr_shi %s rn=%reg_0

MOV_rxri        000 00 ..... ... ...            @shift_i shty=0  # LSL
MOV_rxri        000 01 ..... ... ...            @shift_i shty=1  # LSR
MOV_rxri        000 10 ..... ... ...            @shift_i shty=2  # ASR

# Add/subtract (three low registers)

@addsub_3       ....... rm:3 rn:3 rd:3 \
                &s_rrr_shi %s shim=0 shty=0

ADD_rrri        0001100 ... ... ...             @addsub_3
SUB_rrri        0001101 ... ... ...             @addsub_3

# Add/subtract (two low registers and immediate)

@addsub_2i      ....... imm:3 rn:3 rd:3 \
                &s_rri_rot %s rot=0

ADD_rri         0001 110 ... ... ...            @addsub_2i
SUB_rri         0001 111 ... ... ...            @addsub_2i

# Add, subtract, compare, move (one low register and immediate)

%reg_8          8:3
@arith_1i       ..... rd:3 imm:8 \
                &s_rri_rot rot=0 rn=%reg_8

MOV_rxi         00100 ... ........              @arith_1i %s
CMP_xri         00101 ... ........              @arith_1i s=1
ADD_rri         00110 ... ........              @arith_1i %s
SUB_rri         00111 ... ........              @arith_1i %s

# Add, compare, move (two high registers)

%reg_0_7        7:1 0:3
@addsub_2h      .... .... . rm:4 ... \
                &s_rrr_shi rd=%reg_0_7 rn=%reg_0_7 shim=0 shty=0

ADD_rrri        0100 0100 . .... ...            @addsub_2h s=0
CMP_xrri        0100 0101 . .... ...            @addsub_2h s=1
MOV_rxri        0100 0110 . .... ...            @addsub_2h s=0

# Adjust SP (immediate)

%imm7_0x4       0:7 !function=times_4
@addsub_sp_i    .... .... . ....... \
                &s_rri_rot s=0 rd=13 rn=13 rot=0 imm=%imm7_0x4

ADD_rri         1011 0000 0 .......             @addsub_sp_i
SUB_rri         1011 0000 1 .......             @addsub_sp_i

# Branch and exchange

@branchr        .... .... . rm:4 ...            &r

BX              0100 0111 0 .... 000            @branchr
BLX_r           0100 0111 1 .... 000            @branchr
BXNS            0100 0111 0 .... 100            @branchr
BLXNS           0100 0111 1 .... 100            @branchr

# Extend

@extend         .... .... .. rm:3 rd:3          &rrr_rot rn=15 rot=0

SXTAH           1011 0010 00 ... ...            @extend
SXTAB           1011 0010 01 ... ...            @extend
UXTAH           1011 0010 10 ... ...            @extend
UXTAB           1011 0010 11 ... ...            @extend

# Change processor state

%imod           4:1 !function=plus_2

SETEND          1011 0110 010 1 E:1 000         &setend
{
  CPS           1011 0110 011 . 0 A:1 I:1 F:1   &cps mode=0 M=0 %imod
  CPS_v7m       1011 0110 011 im:1 00 I:1 F:1
}

# Reverse bytes

@rdm            .... .... .. rm:3 rd:3          &rr

REV             1011 1010 00 ... ...            @rdm
REV16           1011 1010 01 ... ...            @rdm
REVSH           1011 1010 11 ... ...            @rdm

# Hints

{
  {
    YIELD       1011 1111 0001 0000
    WFE         1011 1111 0010 0000
    WFI         1011 1111 0011 0000

    # TODO: Implement SEV, SEVL; may help SMP performance.
    # SEV       1011 1111 0100 0000
    # SEVL      1011 1111 0101 0000

    # The canonical nop has the second nibble as 0000, but the whole of the
    # rest of the space is a reserved hint, behaves as nop.
    NOP         1011 1111 ---- 0000
  }
  IT            1011 1111 cond_mask:8
}

# Miscellaneous 16-bit instructions

%imm6_9_3       9:1 3:5 !function=times_2

HLT             1011 1010 10 imm:6              &i
BKPT            1011 1110 imm:8                 &i
CBZ             1011 nz:1 0.1 ..... rn:3        imm=%imm6_9_3

# Push and Pop

%push_list      0:9 !function=t16_push_list
%pop_list       0:9 !function=t16_pop_list

STM             1011 010 ......... \
                &ldst_block i=0 b=1 u=0 w=1 rn=13 list=%push_list
LDM_t16         1011 110 ......... \
                &ldst_block i=1 b=0 u=0 w=1 rn=13 list=%pop_list

# Conditional branches, Supervisor call

%imm8_0x2       0:s8 !function=times_2

{
  UDF           1101 1110 ---- ----
  SVC           1101 1111 imm:8                 &i
  B_cond_thumb  1101 cond:4 ........            &ci imm=%imm8_0x2
}

# Unconditional Branch

%imm11_0x2      0:s11 !function=times_2

B               11100 ...........               &i imm=%imm11_0x2

# thumb_insn_is_16bit() ensures we won't be decoding these as
# T16 instructions for a Thumb2 CPU, so these patterns must be
# a Thumb1 split BL/BLX.
BLX_suffix      11101 imm:11                    &i
BL_BLX_prefix   11110 imm:s11                   &i
BL_suffix       11111 imm:11                    &i