examples: exit via SBI

3 files changed, 76 insertions, 60 deletions

diff --git a/README.rst b/README.rst
index ed8ddd2..23da8ec 100644
--- a/README.rst
+++ b/README.rst
@@ -5,8 +5,8 @@ This is a wip clone of SubX_ for the RISC-V RV32I base ISA.
 
 ::
 
-   $ <hello_world.subv ./validate.py | ./survey.py | ./format.py | ./pack.py | ./elf.py >hello_world.elf
-   $ ./qemu.sh hello_world.elf
+   $ <examples/hello_world.subv ./validate.py | ./survey.py | ./format.py | ./pack.py | ./elf.py >examples/hello_world.elf
+   $ ./qemu.sh examples/hello_world.elf
 
 Pipeline
 --------
@@ -21,69 +21,69 @@ back to front:
 
 and now front to back with a little example::
 
-   $ ./validate.py <ex.subv  >ex.valid
-   $ ./survey.py  <ex.valid  >ex.survey
-   $ ./format.py  <ex.survey >ex.format
-   $ ./pack.py    <ex.format >ex.pack
-   $ ./elf.py     <ex.pack   >ex.elf
+   $ ./validate.py <examples/ex.subv   >examples/ex.valid
+   $ ./survey.py   <examples/ex.valid  >examples/ex.survey
+   $ ./format.py   <examples/ex.survey >examples/ex.format
+   $ ./pack.py     <examples/ex.format >examples/ex.pack
+   $ ./elf.py      <examples/ex.pack   >examples/ex.elf
    $ ./qemu.sh ex.elf
 
 ``ex.subv``: hand-writable::
 
-  == code 0x80000000
-  # repeatedly print "Hi\n"
-  main:
-    # load 0x10010000 (UART0) into t0
-    37/lui 5/rd/t0 0x10010/imm20
-    # store 0x48 (H) in UART0+0
-    13/opi 0/subop/add 6/rd/t1 0/rs/x0 48/imm12
-    23/store 2/width/word 5/rs/t0 6/rs/t1 0/off12
-    # store 0x69 (i) in UART0+0
-    13/opi 0/subop/add 6/rd/t1 0/rs/x0 69/imm12
-    23/store 2/width/word 5/rs/t0 6/rs/t1 0/off12
-    # store 0x0a (\n) in UART0+0
-    13/opi 0/subop/add 6/rd/t1 0/rs/x0 0a/imm12
-    23/store 2/width/word 5/rs/t0 6/rs/t1 0/off12
-    # jump back up to the top
-    6f/jal 0/rd/x0 main/off21
+   == code 0x80400000
+   # repeatedly print "Hi\n"
+   main:
+     # load 0x10000000 (UART0) into t0
+     37/lui 5/rd/t0 10000/imm20
+     # store 0x48 (H) in UART0+0
+     13/opi 0/subop/add 6/rd/t1 0/rs/x0 48/imm12
+     23/store 0/width/byte 5/rs/t0 0/off12 6/rs/t1
+     # store 0x69 (i) in UART0+0
+     13/opi 0/subop/add 6/rd/t1 0/rs/x0 69/imm12
+     23/store 0/width/byte 5/rs/t0 0/off12 6/rs/t1
+     # store 0x0a (\n) in UART0+0
+     13/opi 0/subop/add 6/rd/t1 0/rs/x0 0a/imm12
+     23/store 0/width/byte 5/rs/t0 0/off12 6/rs/t1
+     # jump back up to the top
+     6f/jal 0/rd/x0 main/off21
 
 ``ex.valid``: mnemonics validated and discarded::
 
-  == code 0x80000000
-  # repeatedly print "Hi\n"
-  main:
-  # load 0x10010000 (UART0) into t0
-  37/u 5/rd 10010/imm20
-  # store 0x48 (H) in UART0+0
-  13/i 6/rd 0/funct3 0/rs 48/imm12
-  23/s 5/rs1 0/imm12 2/funct3 6/rs2
-  # store 0x69 (i) in UART0+0
-  13/i 6/rd 0/funct3 0/rs 69/imm12
-  23/s 5/rs1 0/imm12 2/funct3 6/rs2
-  # store 0x0a (\n) in UART0+0
-  13/i 6/rd 0/funct3 0/rs a/imm12
-  23/s 5/rs1 0/imm12 2/funct3 6/rs2
-  # jump back up to the top
-  6f/j 0/rd main/off21
+   == code 0x80400000
+   # repeatedly print "Hi\n"
+   main:
+   # load 0x10000000 (UART0) into t0
+   37/u 5/rd 10000/imm20
+   # store 0x48 (H) in UART0+0
+   13/i 6/rd 0/funct3 0/rs 48/imm12
+   23/s 0/funct3 5/rs1 0/imm12 6/rs2
+   # store 0x69 (i) in UART0+0
+   13/i 6/rd 0/funct3 0/rs 69/imm12
+   23/s 0/funct3 5/rs1 0/imm12 6/rs2
+   # store 0x0a (\n) in UART0+0
+   13/i 6/rd 0/funct3 0/rs a/imm12
+   23/s 0/funct3 5/rs1 0/imm12 6/rs2
+   # jump back up to the top
+   6f/j 0/rd main/off21
 
 ``ex.survey``: references resolved and labels removed::
 
-  == code 0x80000000
-  # repeatedly print "Hi\n"
-  # main:
-  # load 0x10010000 (UART0) into t0
-  37/u 5/rd 10010/imm20
-  # store 0x48 (H) in UART0+0
-  13/i 6/rd 0/funct3 0/rs 48/imm12
-  23/s 5/rs1 0/imm12 2/funct3 6/rs2
-  # store 0x69 (i) in UART0+0
-  13/i 6/rd 0/funct3 0/rs 69/imm12
-  23/s 5/rs1 0/imm12 2/funct3 6/rs2
-  # store 0x0a (\n) in UART0+0
-  13/i 6/rd 0/funct3 0/rs a/imm12
-  23/s 5/rs1 0/imm12 2/funct3 6/rs2
-  # jump back up to the top
-  6f/j 0/rd -1c/imm21
+   == code 0x80400000
+   # repeatedly print "Hi\n"
+   # main:
+   # load 0x10000000 (UART0) into t0
+   37/u 5/rd 10000/imm20
+   # store 0x48 (H) in UART0+0
+   13/i 6/rd 0/funct3 0/rs 48/imm12
+   23/s 0/funct3 5/rs1 0/imm12 6/rs2
+   # store 0x69 (i) in UART0+0
+   13/i 6/rd 0/funct3 0/rs 69/imm12
+   23/s 0/funct3 5/rs1 0/imm12 6/rs2
+   # store 0x0a (\n) in UART0+0
+   13/i 6/rd 0/funct3 0/rs a/imm12
+   23/s 0/funct3 5/rs1 0/imm12 6/rs2
+   # jump back up to the top
+   6f/j 0/rd -1c/imm21
 
 ``ex.format``: arguments sliced and diced and put into the ISA order::
 
diff --git a/examples/ask_name.subv b/examples/ask_name.subv
index f411bfc..dfd5a7a 100644
--- a/examples/ask_name.subv
+++ b/examples/ask_name.subv
@@ -42,8 +42,16 @@ main:
   13/opi a/rd/a0 0/subop/add a/rs/a0 NICETOMEETU/imm12lo
   6f/jal 1/rd/ra print/off21
 
-  # infinite loop
-  6f/jal 0/rd/x0 0/off21
+exit:
+# system reset (via SBI extension SRST)
+  # a7 = ext id, a6 = fid, a0 = 0, a1 = 0
+  37/lui 11/rd/a7 53525/imm20
+  13/opi 11/rd/a7 0/subop/add 11/rs/a7 354/imm12
+  33/opr 0/mode/norm 10/rd/a6 0/subop/add 0/rs/x0 0/rs/x0
+  33/opr 0/mode/norm a/rd/a0 0/subop/add 0/rs/x0 0/rs/x0
+  33/opr 0/mode/norm b/rd/a1 0/subop/add 0/rs/x0 0/rs/x0
+  # ECALL
+  73/system 0/subop/priv 0/funct12/ecall
 
 init:
 # initialize UART0
diff --git a/examples/hello_world.subv b/examples/hello_world.subv
index d25aa83..b85739d 100644
--- a/examples/hello_world.subv
+++ b/examples/hello_world.subv
@@ -11,9 +11,17 @@ main:
   13/opi a/rd/a0 0/subop/add a/rs/a0 Message/imm12lo
   # call print
   6f/jal 1/rd/ra print/off21
-loop:
-  # infinite loop
-  6f/jal 0/rd/x0 main/off21
+
+exit:
+# system reset (via SBI extension SRST)
+  # a7 = ext id, a6 = fid, a0 = 0, a1 = 0
+  37/lui 11/rd/a7 53525/imm20
+  13/opi 11/rd/a7 0/subop/add 11/rs/a7 354/imm12
+  33/opr 0/mode/norm 10/rd/a6 0/subop/add 0/rs/x0 0/rs/x0
+  33/opr 0/mode/norm a/rd/a0 0/subop/add 0/rs/x0 0/rs/x0
+  33/opr 0/mode/norm b/rd/a1 0/subop/add 0/rs/x0 0/rs/x0
+  # ECALL
+  73/system 0/subop/priv 0/funct12/ecall
 
 print:
   # load 0x10000000 (UART0) into t0