checksumm.h

00001 /*
00002     This file is part of Smoothie (http://smoothieware.org/)
00003     The motion control part is heavily based on Grbl (https://github.com/simen/grbl)
00004 
00005     Smoothie is free software: you can redistribute it and/or modify it under
00006     the terms of the GNU General Public License as published by the Free
00007     Software Foundation, either version 3 of the License, or (at your option)
00008     any later version.
00009 
00010     Smoothie is distributed in the hope that it will be useful, but WITHOUT ANY
00011     WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
00012     FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
00013     details.
00014 
00015     You should have received a copy of the GNU General Public License along
00016     with Smoothie. If not, see <http://www.gnu.org/licenses/>.
00017 */
00018 /* Calculates Fletcher Checksum at compile time using recursive macros. */
00019 #ifndef _CHECKSUM_MACRO_H_
00020 #define _CHECKSUM_MACRO_H_
00021 
00022 /* There are two compile time checksumming approaches in this file.  One uses
00023    the C preprocessor and the other uses new C++11 features.  They should both
00024    do the same thing but my current compiler, GCC 4.7, doesn't always do the
00025    constant folding for the C++ approach and this causes code bloat.  The C 
00026    preprocessor approach can currently generate the exact same code in 
00027    Checked/Release builds as the old method of pre-calculating checksums by 
00028    hand and pasting them into the code.
00029    
00030    Keeping both versions here: the active C version and the C++ version
00031    that we should switch to later if newer compilers do the required constant
00032    folding (maybe there are optimization flags to help here.)
00033 */
00034 #ifdef CHECKSUM_USE_CPP
00035 
00036 #include <type_traits>
00037 
00038 /* Cool C++11 approach contributed by bgamari on #smoothieware IRC channel.
00039  * Unfortunately this will have to wait until after we switch to GCC 4.7.
00040  */
00041 constexpr uint16_t checksum(const char* s, size_t n, size_t i, uint16_t sum1, uint16_t sum2) {
00042   return (i <= n) ? checksum(s, n, i+1, (sum1 + s[i]) % 255, (sum2 + sum1) % 255) : ((sum2 << 8) | sum1);
00043 }
00044 
00045 constexpr uint16_t operator "" _checksum(const char* s, size_t n) {
00046   return checksum(s, n, 0, 0, 0);
00047 }
00048 
00049 #define CHECKSUM(X) std::integral_constant<uint16_t, X##_checksum>::value
00050 
00051 #else /* !CHECKSUM_USE_CPP */
00052 
00053 /* Adam Green's old and crusty C approach. */
00054 /* Recursively define SUM1, the basic checksum % 255 */
00055 #define SUM1_1(X) ((X)[0] % 255)
00056 #define SUM1_2(X) ((SUM1_1(X) + (X)[1]) % 255)
00057 #define SUM1_3(X) ((SUM1_2(X) + (X)[2]) % 255)
00058 #define SUM1_4(X) ((SUM1_3(X) + (X)[3]) % 255)
00059 #define SUM1_5(X) ((SUM1_4(X) + (X)[4]) % 255)
00060 #define SUM1_6(X) ((SUM1_5(X) + (X)[5]) % 255)
00061 #define SUM1_7(X) ((SUM1_6(X) + (X)[6]) % 255)
00062 #define SUM1_8(X) ((SUM1_7(X) + (X)[7]) % 255)
00063 #define SUM1_9(X) ((SUM1_8(X) + (X)[8]) % 255)
00064 #define SUM1_10(X) ((SUM1_9(X) + (X)[9]) % 255)
00065 #define SUM1_11(X) ((SUM1_10(X) + (X)[10]) % 255)
00066 #define SUM1_12(X) ((SUM1_11(X) + (X)[11]) % 255)
00067 #define SUM1_13(X) ((SUM1_12(X) + (X)[12]) % 255)
00068 #define SUM1_14(X) ((SUM1_13(X) + (X)[13]) % 255)
00069 #define SUM1_15(X) ((SUM1_14(X) + (X)[14]) % 255)
00070 #define SUM1_16(X) ((SUM1_15(X) + (X)[15]) % 255)
00071 #define SUM1_17(X) ((SUM1_16(X) + (X)[16]) % 255)
00072 #define SUM1_18(X) ((SUM1_17(X) + (X)[17]) % 255)
00073 #define SUM1_19(X) ((SUM1_18(X) + (X)[18]) % 255)
00074 #define SUM1_20(X) ((SUM1_19(X) + (X)[19]) % 255)
00075 #define SUM1_21(X) ((SUM1_20(X) + (X)[20]) % 255)
00076 #define SUM1_22(X) ((SUM1_21(X) + (X)[21]) % 255)
00077 #define SUM1_23(X) ((SUM1_22(X) + (X)[22]) % 255)
00078 #define SUM1_24(X) ((SUM1_23(X) + (X)[23]) % 255)
00079 #define SUM1_25(X) ((SUM1_24(X) + (X)[24]) % 255)
00080 #define SUM1_26(X) ((SUM1_25(X) + (X)[25]) % 255)
00081 #define SUM1_27(X) ((SUM1_26(X) + (X)[26]) % 255)
00082 #define SUM1_28(X) ((SUM1_27(X) + (X)[27]) % 255)
00083 #define SUM1_29(X) ((SUM1_28(X) + (X)[28]) % 255)
00084 #define SUM1_30(X) ((SUM1_29(X) + (X)[29]) % 255)
00085 #define SUM1_31(X) ((SUM1_30(X) + (X)[30]) % 255)
00086 #define SUM1_32(X) ((SUM1_31(X) + (X)[31]) % 255)
00087 
00088 /* Recursively define SUM2, the sum of SUM1s % 255 */
00089 #define SUM2_1(X) (SUM1_1(X) % 255)
00090 #define SUM2_2(X) ((SUM2_1(X) + SUM1_2(X)) % 255)
00091 #define SUM2_3(X) ((SUM2_2(X) + SUM1_3(X)) % 255)
00092 #define SUM2_4(X) ((SUM2_3(X) + SUM1_4(X)) % 255)
00093 #define SUM2_5(X) ((SUM2_4(X) + SUM1_5(X)) % 255)
00094 #define SUM2_6(X) ((SUM2_5(X) + SUM1_6(X)) % 255)
00095 #define SUM2_7(X) ((SUM2_6(X) + SUM1_7(X)) % 255)
00096 #define SUM2_8(X) ((SUM2_7(X) + SUM1_8(X)) % 255)
00097 #define SUM2_9(X) ((SUM2_8(X) + SUM1_9(X)) % 255)
00098 #define SUM2_10(X) ((SUM2_9(X) + SUM1_10(X)) % 255)
00099 #define SUM2_11(X) ((SUM2_10(X) + SUM1_11(X)) % 255)
00100 #define SUM2_12(X) ((SUM2_11(X) + SUM1_12(X)) % 255)
00101 #define SUM2_13(X) ((SUM2_12(X) + SUM1_13(X)) % 255)
00102 #define SUM2_14(X) ((SUM2_13(X) + SUM1_14(X)) % 255)
00103 #define SUM2_15(X) ((SUM2_14(X) + SUM1_15(X)) % 255)
00104 #define SUM2_16(X) ((SUM2_15(X) + SUM1_16(X)) % 255)
00105 #define SUM2_17(X) ((SUM2_16(X) + SUM1_17(X)) % 255)
00106 #define SUM2_18(X) ((SUM2_17(X) + SUM1_18(X)) % 255)
00107 #define SUM2_19(X) ((SUM2_18(X) + SUM1_19(X)) % 255)
00108 #define SUM2_20(X) ((SUM2_19(X) + SUM1_20(X)) % 255)
00109 #define SUM2_21(X) ((SUM2_20(X) + SUM1_21(X)) % 255)
00110 #define SUM2_22(X) ((SUM2_21(X) + SUM1_22(X)) % 255)
00111 #define SUM2_23(X) ((SUM2_22(X) + SUM1_23(X)) % 255)
00112 #define SUM2_24(X) ((SUM2_23(X) + SUM1_24(X)) % 255)
00113 #define SUM2_25(X) ((SUM2_24(X) + SUM1_25(X)) % 255)
00114 #define SUM2_26(X) ((SUM2_25(X) + SUM1_26(X)) % 255)
00115 #define SUM2_27(X) ((SUM2_26(X) + SUM1_27(X)) % 255)
00116 #define SUM2_28(X) ((SUM2_27(X) + SUM1_28(X)) % 255)
00117 #define SUM2_29(X) ((SUM2_28(X) + SUM1_29(X)) % 255)
00118 #define SUM2_30(X) ((SUM2_29(X) + SUM1_30(X)) % 255)
00119 #define SUM2_31(X) ((SUM2_30(X) + SUM1_31(X)) % 255)
00120 #define SUM2_32(X) ((SUM2_31(X) + SUM1_32(X)) % 255)
00121 
00122 /* Define overall checksum as 16-bit combination of SUM1 in lower 8-bits and SUM2 in upper 8-bits. */
00123 #define CHECKSUM_(SUM1,SUM2) (SUM1) | (SUM2 << 8)
00124 #define CHECKSUM_1(X) CHECKSUM_(SUM1_1(X),SUM2_1(X))
00125 #define CHECKSUM_2(X) CHECKSUM_(SUM1_2(X),SUM2_2(X))
00126 #define CHECKSUM_3(X) CHECKSUM_(SUM1_3(X),SUM2_3(X))
00127 #define CHECKSUM_4(X) CHECKSUM_(SUM1_4(X),SUM2_4(X))
00128 #define CHECKSUM_5(X) CHECKSUM_(SUM1_5(X),SUM2_5(X))
00129 #define CHECKSUM_6(X) CHECKSUM_(SUM1_6(X),SUM2_6(X))
00130 #define CHECKSUM_7(X) CHECKSUM_(SUM1_7(X),SUM2_7(X))
00131 #define CHECKSUM_8(X) CHECKSUM_(SUM1_8(X),SUM2_8(X))
00132 #define CHECKSUM_9(X) CHECKSUM_(SUM1_9(X),SUM2_9(X))
00133 #define CHECKSUM_10(X) CHECKSUM_(SUM1_10(X),SUM2_10(X))
00134 #define CHECKSUM_11(X) CHECKSUM_(SUM1_11(X),SUM2_11(X))
00135 #define CHECKSUM_12(X) CHECKSUM_(SUM1_12(X),SUM2_12(X))
00136 #define CHECKSUM_13(X) CHECKSUM_(SUM1_13(X),SUM2_13(X))
00137 #define CHECKSUM_14(X) CHECKSUM_(SUM1_14(X),SUM2_14(X))
00138 #define CHECKSUM_15(X) CHECKSUM_(SUM1_15(X),SUM2_15(X))
00139 #define CHECKSUM_16(X) CHECKSUM_(SUM1_16(X),SUM2_16(X))
00140 #define CHECKSUM_17(X) CHECKSUM_(SUM1_17(X),SUM2_17(X))
00141 #define CHECKSUM_18(X) CHECKSUM_(SUM1_18(X),SUM2_18(X))
00142 #define CHECKSUM_19(X) CHECKSUM_(SUM1_19(X),SUM2_19(X))
00143 #define CHECKSUM_20(X) CHECKSUM_(SUM1_20(X),SUM2_20(X))
00144 #define CHECKSUM_21(X) CHECKSUM_(SUM1_21(X),SUM2_21(X))
00145 #define CHECKSUM_22(X) CHECKSUM_(SUM1_22(X),SUM2_22(X))
00146 #define CHECKSUM_23(X) CHECKSUM_(SUM1_23(X),SUM2_23(X))
00147 #define CHECKSUM_24(X) CHECKSUM_(SUM1_24(X),SUM2_24(X))
00148 #define CHECKSUM_25(X) CHECKSUM_(SUM1_25(X),SUM2_25(X))
00149 #define CHECKSUM_26(X) CHECKSUM_(SUM1_26(X),SUM2_26(X))
00150 #define CHECKSUM_27(X) CHECKSUM_(SUM1_27(X),SUM2_27(X))
00151 #define CHECKSUM_28(X) CHECKSUM_(SUM1_28(X),SUM2_28(X))
00152 #define CHECKSUM_29(X) CHECKSUM_(SUM1_29(X),SUM2_29(X))
00153 #define CHECKSUM_30(X) CHECKSUM_(SUM1_30(X),SUM2_30(X))
00154 #define CHECKSUM_31(X) CHECKSUM_(SUM1_31(X),SUM2_31(X))
00155 #define CHECKSUM_32(X) CHECKSUM_(SUM1_32(X),SUM2_32(X))
00156 
00157 #ifdef DEBUG
00158 
00159 #include <utils.h>
00160 #define CHECKSUM(X) get_checksum(X)
00161 
00162 #else /* !DEBUG */
00163 
00164 #define CHECKSUM(X) (sizeof(X) == 0 ? 0 : \
00165                      sizeof(X) == 1 ? 0 : \
00166                      sizeof(X) == 2 ? CHECKSUM_1(X) : \
00167                      sizeof(X) == 3 ? CHECKSUM_2(X) : \
00168                      sizeof(X) == 4 ? CHECKSUM_3(X) : \
00169                      sizeof(X) == 5 ? CHECKSUM_4(X) : \
00170                      sizeof(X) == 6 ? CHECKSUM_5(X) : \
00171                      sizeof(X) == 7 ? CHECKSUM_6(X) : \
00172                      sizeof(X) == 8 ? CHECKSUM_7(X) : \
00173                      sizeof(X) == 9 ? CHECKSUM_8(X) : \
00174                      sizeof(X) == 10 ? CHECKSUM_9(X) : \
00175                      sizeof(X) == 11 ? CHECKSUM_10(X) : \
00176                      sizeof(X) == 12 ? CHECKSUM_11(X) : \
00177                      sizeof(X) == 13 ? CHECKSUM_12(X) : \
00178                      sizeof(X) == 14 ? CHECKSUM_13(X) : \
00179                      sizeof(X) == 15 ? CHECKSUM_14(X) : \
00180                      sizeof(X) == 16 ? CHECKSUM_15(X) : \
00181                      sizeof(X) == 17 ? CHECKSUM_16(X) : \
00182                      sizeof(X) == 18 ? CHECKSUM_17(X) : \
00183                      sizeof(X) == 19 ? CHECKSUM_18(X) : \
00184                      sizeof(X) == 20 ? CHECKSUM_19(X) : \
00185                      sizeof(X) == 21 ? CHECKSUM_20(X) : \
00186                      sizeof(X) == 22 ? CHECKSUM_21(X) : \
00187                      sizeof(X) == 23 ? CHECKSUM_22(X) : \
00188                      sizeof(X) == 24 ? CHECKSUM_23(X) : \
00189                      sizeof(X) == 25 ? CHECKSUM_24(X) : \
00190                      sizeof(X) == 26 ? CHECKSUM_25(X) : \
00191                      sizeof(X) == 27 ? CHECKSUM_26(X) : \
00192                      sizeof(X) == 28 ? CHECKSUM_27(X) : \
00193                      sizeof(X) == 29 ? CHECKSUM_28(X) : \
00194                      sizeof(X) == 30 ? CHECKSUM_29(X) : \
00195                      sizeof(X) == 31 ? CHECKSUM_30(X) : \
00196                      sizeof(X) == 32 ? CHECKSUM_31(X) : \
00197                      sizeof(X) == 33 ? CHECKSUM_32(X) : \
00198                      0xFFFF)
00199 #endif /* DEBUG */
00200 #endif /* CHECKSUM_USE_CPP */
00201 
00202 #endif /* _CHECKSUM_MACRO_H_ */