wire_read.h

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#pragma once
#include <stdbool.h>
#include <stdint.h>
 
#include "io/bytes_le.h"


static inline int32_t wire_int_or(bool is_signed, uint16_t length, const uint8_t *value, int32_t fallback)
{
    if (!value)
    {
        return fallback;
    }
 
    switch (length)
    {
        // a byte read signed is -128 to 127 and unsigned is 0 to 255
        // that is the only thing the signedness decides at this width
        case 1: return is_signed ? (int32_t)(int8_t)value[0] : (int32_t)value[0];
 
        // read the pair as signed and take the sign back off when it is not wanted
        // so the unsigned half lands on 0 to 65535 rather than going negative at the top
        case 2: return is_signed ? (int32_t)read_i16_le(value)
                                 : (int32_t)(uint16_t)read_i16_le(value);
 
        // four bytes fill the whole width either way so the bits are the same
        // and only the caller's reading of the top one differs
        case 4: return read_i32_le(value);
 
        default: return fallback;
    }
}

static inline bool wire_cstring_terminated(const char *s, uint16_t length)
{
    return s && length > 0 && s[length - 1] == '\0';
}