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This commit is contained in:
Kartik Agaram 2020-07-18 15:56:32 -07:00
parent 28b25a4893
commit 02b7f9bd89
2 changed files with 7 additions and 7 deletions
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2
120allocate.subx
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@ -855,7 +855,7 @@ test-copy-array:
e8/call check-ints-equal/disp32 e8/call check-ints-equal/disp32
# . . discard args # . . discard args
81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp 81 0/subop/add 3/mod/direct 4/rm32/esp . . . . . 0xc/imm32 # add to esp
# check-ints-equal(ad->curr - expected-payload, 12 + 4 for alloc-id + 4 for length, msg) # check-ints-equal(ad->curr - expected-payload, 12 + 4 for alloc-id + 4 for size, msg)
# . . push args # . . push args
68/push "F - test-copy-array: updates allocation descriptor"/imm32 68/push "F - test-copy-array: updates allocation descriptor"/imm32
68/push 0x14/imm32 68/push 0x14/imm32

12
vocabulary.md
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@ -5,9 +5,9 @@
- Kernel strings: null-terminated regions of memory. Unsafe and to be avoided, - Kernel strings: null-terminated regions of memory. Unsafe and to be avoided,
but needed for interacting with the kernel. but needed for interacting with the kernel.
- Arrays: length-prefixed regions of memory containing multiple elements of a - Arrays: size-prefixed regions of memory containing multiple elements of a
single type. Contents are preceded by 4 bytes (32 bits) containing the single type. Contents are preceded by 4 bytes (32 bits) containing the
`length` of the array in bytes. `size` of the array in bytes.
- Slices: a pair of 32-bit addresses denoting a [half-open](https://en.wikipedia.org/wiki/Interval_(mathematics)) - Slices: a pair of 32-bit addresses denoting a [half-open](https://en.wikipedia.org/wiki/Interval_(mathematics))
\[`start`, `end`) interval to live memory with a consistent lifetime. \[`start`, `end`) interval to live memory with a consistent lifetime.
@ -19,10 +19,10 @@
- offset 0: write index - offset 0: write index
- offset 4: read index - offset 4: read index
- offset 8: length of array (in bytes) - offset 8: size of array (in bytes)
- offset 12: start of array data - offset 12: start of array data
Invariant: 0 <= `read` <= `write` <= `length` Invariant: 0 <= `read` <= `write` <= `size`
- File descriptors (fd): Low-level 32-bit integers that the kernel uses to - File descriptors (fd): Low-level 32-bit integers that the kernel uses to
track files opened by the program. track files opened by the program.
@ -51,7 +51,7 @@ But those are big goals. Here are the syscalls I have so far:
1. SubX can handle 'fake' file descriptors in tests. 1. SubX can handle 'fake' file descriptors in tests.
1. `write()` accepts buffer and its length in separate arguments, which 1. `write()` accepts buffer and its size in separate arguments, which
requires callers to manage the two separately and so can be error-prone. requires callers to manage the two separately and so can be error-prone.
SubX's wrapper keeps the two together to increase the chances that we SubX's wrapper keeps the two together to increase the chances that we
never accidentally go out of array bounds. never accidentally go out of array bounds.
@ -178,7 +178,7 @@ allocated memory for it.)_
- `new-stream`: allocates space for a stream of `n` elements, each occupying - `new-stream`: allocates space for a stream of `n` elements, each occupying
`b` bytes. `b` bytes.
- Will abort the entire program if `n*b` requires more than 32 bits. - Will abort the entire program if `n*b` requires more than 32 bits.
- `clear-stream`: resets everything in the stream to `0` (except its `length`). - `clear-stream`: resets everything in the stream to `0` (except its `size`).
- `rewind-stream`: resets the read index of the stream to `0` without modifying - `rewind-stream`: resets the read index of the stream to `0` without modifying
its contents. its contents.