From 683f205402a99cfc8cea46c83ce9b46a42616d42 Mon Sep 17 00:00:00 2001 From: Mattias Andrée Date: Sat, 16 Dec 2023 12:40:10 +0100 Subject: All kinds of stuff MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Signed-off-by: Mattias Andrée --- libsyscalls_parse_signed_integer.c | 61 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 61 insertions(+) create mode 100644 libsyscalls_parse_signed_integer.c (limited to 'libsyscalls_parse_signed_integer.c') diff --git a/libsyscalls_parse_signed_integer.c b/libsyscalls_parse_signed_integer.c new file mode 100644 index 0000000..da6f078 --- /dev/null +++ b/libsyscalls_parse_signed_integer.c @@ -0,0 +1,61 @@ +/* See LICENSE file for copyright and license details. */ +#include "common.h" + + +enum libsyscalls_error +libsyscalls_parse_signed_integer(unsigned long long int value_in, enum libsyscalls_datatype_sign_representation representation, + size_t bits, unsigned long long int *value_out, int *negative_out) +{ + unsigned long long int value = value_in, mask; + int negative = 0; + + if (!bits || bits > sizeof(value) / sizeof(char) * CHAR_BIT) + return LIBSYSCALLS_E_INVAL; + + switch (representation) { + case LIBSYSCALLS_SIGN_UNDETERMINED: + break; + + case LIBSYSCALLS_SIGN_TWOS_COMPLEMENT: + if (value >> (bits - 1U)) { + mask = (1ULL << (bits - 1U)) - 1ULL; + value = ~value & mask; + value += 1ULL; + negative = 1; + } + break; + + case LIBSYSCALLS_SIGN_ONES_COMPLEMENT: + if (value >> (bits - 1U)) { + mask = (1ULL << (bits - 1U)) - 1ULL; + value = ~value & mask; + negative = 1; + } + break; + + case LIBSYSCALLS_SIGN_SIGN_MAGNITUDE: + if (value >> (bits - 1U)) { + value ^= 1ULL << (bits - 1U); + negative = 1; + } + break; + + case LIBSYSCALLS_SIGN_EXCESS_HALF: + if (value >> (bits - 1U)) { + value ^= 1ULL << (bits - 1U); + } else { + value = (1ULL << (bits - 1U)) - value; + negative = 1; + } + break; + + default: + return LIBSYSCALLS_E_INVAL; + } + + if (value_out) + *value_out = value; + if (negative_out) + *negative_out = negative; + return LIBSYSCALLS_E_OK; +} -- cgit v1.2.3-70-g09d2