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Some documentations about C stubs

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This commit is contained in:
Calascibetta Romain 2024-12-05 16:14:09 +01:00
parent 1bba186313
commit d003b295a2
1 changed files with 28 additions and 4 deletions
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32
lib/stubs.solo5.c
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@ -3,11 +3,26 @@
#include <caml/memory.h>
#include <caml/bigarray.h>
/* We currently have no need for these functions. They consist of releasing the
* GC lock when we do operations with Solo5 with bigstrings, because of the
* quality of bigstrings, we can execute these operations after informing OCaml
* that it can do the work it wants on the GC in parallel. However, we don't
* have parallelism with Solo5. This comment is to explain why we don't use
* them when we could. */
extern void caml_enter_blocking_section(void);
extern void caml_leave_blocking_section(void);
intnat miou_solo5_block_read(solo5_handle_t handle, intnat off, intnat len,
/* Note between solo5_handle_t and intnat. Currently, solo5_handle_t is an
* integer 64, but Solo5 cannot manage more than 64 devices at the same time.
* More practically, it would be difficult to make a unikernel that needed 64
* or even 63 different devices. We can afford to lose one bit for both
* solo5_handle_t (which represents our file-descriptors) and
* solo5_handle_set_t, which can only contain file-descriptors with a value
* between 0 and 63. */
intnat miou_solo5_block_read(intnat fd, intnat off, intnat len,
value vbstr) {
solo5_handle_t handle = fd;
solo5_off_t offset = off;
size_t size = len;
solo5_result_t result;
@ -16,8 +31,9 @@ intnat miou_solo5_block_read(solo5_handle_t handle, intnat off, intnat len,
return result;
}
intnat miou_solo5_block_write(solo5_handle_t handle, intnat off, intnat len,
intnat miou_solo5_block_write(intnat fd, intnat off, intnat len,
value vbstr) {
solo5_handle_t handle = fd;
solo5_off_t offset = off;
size_t size = len;
solo5_result_t result;
@ -26,9 +42,16 @@ intnat miou_solo5_block_write(solo5_handle_t handle, intnat off, intnat len,
return result;
}
intnat miou_solo5_net_read(solo5_handle_t handle, intnat off, intnat len,
/* Instead of passing the [read_size] result in data that would be allocated on
* the C side, the OCaml side allocates a small buffer of 8 bytes to store the
* number of bytes that Solo5 was able to read. memcpy saves our result in this
* small buffer and, on the OCaml side, we just need to read it. It's a bit
* like the poor man's C-style reference passage in OCaml. */
intnat miou_solo5_net_read(intnat fd, intnat off, intnat len,
value vread_size, value vbstr) {
CAMLparam1(vread_size);
solo5_handle_t handle = fd;
size_t size = len;
size_t read_size;
solo5_result_t result;
@ -38,8 +61,9 @@ intnat miou_solo5_net_read(solo5_handle_t handle, intnat off, intnat len,
CAMLreturn(Val_long(result));
}
intnat miou_solo5_net_write(solo5_handle_t handle, intnat off, intnat len,
intnat miou_solo5_net_write(intnat fd, intnat off, intnat len,
value vbstr) {
solo5_handle_t handle = fd;
size_t size = len;
solo5_result_t result;
uint8_t *buf = (uint8_t *)Caml_ba_data_val(vbstr) + off;