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Add helper functions for reading binary numbers

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And make use of them.
This commit is contained in:
Přemysl Eric Janouch
2024-02-10 07:02:54 +01:00
parent c5424e6992
commit f32bcbd7f4
2 changed files with 60 additions and 18 deletions
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2
LICENSE
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@@ -1,4 +1,4 @@
Copyright (c) 2014 - 2023, Přemysl Eric Janouch <p@janouch.name>
Copyright (c) 2014 - 2024, Přemysl Eric Janouch <p@janouch.name>
Permission to use, copy, modify, and/or distribute this software for any
purpose with or without fee is hereby granted.

76
liberty.c
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@@ -1,7 +1,7 @@
/*
* liberty.c: the ultimate C unlibrary
*
* Copyright (c) 2014 - 2022, Přemysl Eric Janouch <p@janouch.name>
* Copyright (c) 2014 - 2024, Přemysl Eric Janouch <p@janouch.name>
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted.
@@ -652,6 +652,60 @@ str_pack_u64 (struct str *self, uint64_t x)
#define str_pack_i32(self, x) str_pack_u32 ((self), (uint32_t) (x))
#define str_pack_i64(self, x) str_pack_u64 ((self), (uint64_t) (x))
// --- Reading binary numbers --------------------------------------------------
// Doing this byte by byte prevents unaligned memory access issues.
static uint64_t
peek_u64be (const uint8_t *p)
{
return (uint64_t) p[0] << 56 | (uint64_t) p[1] << 48
| (uint64_t) p[2] << 40 | (uint64_t) p[3] << 32
| (uint64_t) p[4] << 24 | (uint64_t) p[5] << 16 | p[6] << 8 | p[7];
}
static uint32_t
peek_u32be (const uint8_t *p)
{
return (uint32_t) p[0] << 24 | (uint32_t) p[1] << 16 | p[2] << 8 | p[3];
}
static uint16_t
peek_u16be (const uint8_t *p)
{
return (uint16_t) p[0] << 8 | p[1];
}
static uint64_t
peek_u64le (const uint8_t *p)
{
return (uint64_t) p[7] << 56 | (uint64_t) p[6] << 48
| (uint64_t) p[5] << 40 | (uint64_t) p[4] << 32
| (uint64_t) p[3] << 24 | (uint64_t) p[2] << 16 | p[1] << 8 | p[0];
}
static uint32_t
peek_u32le (const uint8_t *p)
{
return (uint32_t) p[3] << 24 | (uint32_t) p[2] << 16 | p[1] << 8 | p[0];
}
static uint16_t
peek_u16le (const uint8_t *p)
{
return (uint16_t) p[1] << 8 | p[0];
}
struct peeker
{
uint64_t (*u64) (const uint8_t *);
uint32_t (*u32) (const uint8_t *);
uint16_t (*u16) (const uint8_t *);
};
static const struct peeker peeker_be = {peek_u64be, peek_u32be, peek_u16be};
static const struct peeker peeker_le = {peek_u64le, peek_u32le, peek_u16le};
// --- Errors ------------------------------------------------------------------
// Error reporting utilities. Inspired by GError, only much simpler.
@@ -2503,12 +2557,7 @@ msg_reader_get (struct msg_reader *self, size_t *len)
return NULL;
uint8_t *x = (uint8_t *) self->buf.str + self->offset;
uint64_t msg_len
= (uint64_t) x[0] << 56 | (uint64_t) x[1] << 48
| (uint64_t) x[2] << 40 | (uint64_t) x[3] << 32
| (uint64_t) x[4] << 24 | (uint64_t) x[5] << 16
| (uint64_t) x[6] << 8 | (uint64_t) x[7];
uint64_t msg_len = peek_u64be (x);
if (msg_len < sizeof msg_len)
{
// The message is shorter than its header
@@ -2573,8 +2622,7 @@ static bool
msg_unpacker_u16 (struct msg_unpacker *self, uint16_t *value)
{
UNPACKER_INT_BEGIN
*value
= (uint16_t) x[0] << 8 | (uint16_t) x[1];
*value = peek_u16be (x);
return true;
}
@@ -2582,9 +2630,7 @@ static bool
msg_unpacker_u32 (struct msg_unpacker *self, uint32_t *value)
{
UNPACKER_INT_BEGIN
*value
= (uint32_t) x[0] << 24 | (uint32_t) x[1] << 16
| (uint32_t) x[2] << 8 | (uint32_t) x[3];
*value = peek_u32be (x);
return true;
}
@@ -2592,11 +2638,7 @@ static bool
msg_unpacker_u64 (struct msg_unpacker *self, uint64_t *value)
{
UNPACKER_INT_BEGIN
*value
= (uint64_t) x[0] << 56 | (uint64_t) x[1] << 48
| (uint64_t) x[2] << 40 | (uint64_t) x[3] << 32
| (uint64_t) x[4] << 24 | (uint64_t) x[5] << 16
| (uint64_t) x[6] << 8 | (uint64_t) x[7];
*value = peek_u64be (x);
return true;
}