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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
# . . discard args
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
68/push "F - test-copy-array: updates allocation descriptor"/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,
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
`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))
\[`start`, `end`) interval to live memory with a consistent lifetime.
@ -19,10 +19,10 @@
- offset 0: write 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
Invariant: 0 <= `read` <= `write` <= `length`
Invariant: 0 <= `read` <= `write` <= `size`
- File descriptors (fd): Low-level 32-bit integers that the kernel uses to
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. `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.
SubX's wrapper keeps the two together to increase the chances that we
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
`b` bytes.
- 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
its contents.