diff options
| author | Kathy Gray | 2015-06-16 17:05:16 +0100 |
|---|---|---|
| committer | Kathy Gray | 2015-06-16 17:05:16 +0100 |
| commit | e514087d97ec10618248f04ebc07be57d2d75acd (patch) | |
| tree | f58f679fe748a9a16b36e8f3217f5af68a4b9946 /src | |
| parent | 8e84dc526366d3db615d9f5e7e166ae59dd9ff80 (diff) | |
Incorporate comments from Peter.
Add a flag type for endian, not used yet
Diffstat (limited to 'src')
| -rw-r--r-- | src/lem_interp/interp_interface.lem | 23 |
1 files changed, 20 insertions, 3 deletions
diff --git a/src/lem_interp/interp_interface.lem b/src/lem_interp/interp_interface.lem index d2684553..374f633e 100644 --- a/src/lem_interp/interp_interface.lem +++ b/src/lem_interp/interp_interface.lem @@ -53,6 +53,10 @@ type direction = | D_increasing | D_decreasing +type end_flag = + | E_big_endian + | E_little_endian + type register_value = <| rv_bits: list bit_lifted (* MSB first, smallest index number *); rv_dir: direction; @@ -62,17 +66,30 @@ type register_value = <| Otherwise, tells interpreter how to reconstruct a proper decreasing value*) |> -type byte_lifted = Byte_lifted of list bit_lifted (* of length 8 *) +type byte_lifted = Byte_lifted of list bit_lifted (* of length 8 *) (*MSB first everywhere*) type instruction_field_value = list bit -type byte = Byte of list bit (* of length 8 *) (*MSB first*) +type byte = Byte of list bit (* of length 8 *) (*MSB first everywhere*) type address_lifted = Address_lifted of list byte_lifted (* of length 8 for 64bit machines*) * maybe integer type memory_byte = byte_lifted -type memory_value = list memory_byte (* the head of the list, most-significant first, at the lowest address, of length >=1 *) +type memory_value = list memory_byte +(* the list is of length >=1 *) +(* for both big-endian (Power) and little-endian (ARM), the head of the + list is the byte stored at the lowest address *) +(* for big-endian Power the head of the list is the most-significant + byte, in both the interpreter and machineDef* code. *) +(* For little-endian ARM, the head of the list is the + least-significant byte in machineDef* code and the + most-significant byte in interpreter code, with the switch over + (a list-reverse) being done just inside the interpreter interface*) +(* In other words, in the machineDef* code the lowest-address byte is first, + and in the interpreter code the most-significant byte is first *) + + (* not sure which of these is more handy yet *) type address = Address of list byte (* of length 8 *) * integer |