diff options
Diffstat (limited to 'lib/util/intcode.h')
-rw-r--r-- | lib/util/intcode.h | 77 |
1 files changed, 74 insertions, 3 deletions
diff --git a/lib/util/intcode.h b/lib/util/intcode.h index 4d9c83aa..a171d4e0 100644 --- a/lib/util/intcode.h +++ b/lib/util/intcode.h @@ -3,6 +3,9 @@ #include "pm_config.h" /* For uint32_t, BYTE_ORDER */ +unsigned int const pm_byteOrder = BYTE_ORDER; + + typedef struct { /*---------------------------------------------------------------------------- This is a big-endian representation of a 32 bit integer. I.e. @@ -20,9 +23,6 @@ typedef struct { } bigend32; -unsigned int const pm_byteOrder = BYTE_ORDER; - - static __inline__ uint32_t pm_uintFromBigend32(bigend32 const arg) { @@ -83,4 +83,75 @@ pm_bigendFromUint32(uint32_t const arg) { return retval; } +typedef struct { +/*---------------------------------------------------------------------------- + This is a big-endian representation of a 16 bit integer. I.e. + bytes[0] is the most significant 8 bits; bytes[1] is the least + significant 8 bits of the number in pure binary. + + On a big-endian machines, this is bit for bit identical to uint16_t. + On a little-endian machine, it isn't. + + This is an important data type because decent file formats use + big-endian -- they don't care if some CPU happens to use some other + code for its own work. +-----------------------------------------------------------------------------*/ + unsigned char bytes[2]; +} bigend16; + + +static __inline__ uint16_t +pm_uintFromBigend16(bigend16 const arg) { + + uint16_t retval; + + switch (pm_byteOrder) { + case BIG_ENDIAN: { + union { + bigend16 bigend; + uint16_t native; + } converter; + + converter.bigend = arg; + + retval = converter.native; + }; break; + case LITTLE_ENDIAN: { + retval = + (arg.bytes[0] << 16) | + (arg.bytes[1] << 8); + } break; + } + return retval; +} + + + +static __inline__ bigend16 +pm_bigendFromUint16(uint16_t const arg) { + + bigend16 retval; + + switch (pm_byteOrder) { + case BIG_ENDIAN: { + union { + bigend16 bigend; + uint16_t native; + } converter; + + converter.native = arg; + + retval = converter.bigend; + } break; + case LITTLE_ENDIAN: { + uint16_t shift; + shift = arg; + retval.bytes[1] = shift; /* Takes lower 8 bits */ + shift >>= 8; + retval.bytes[0] = shift; /* Takes lower 8 bits */ + } break; + } + return retval; +} + #endif |