include/pg_config.h 14: #define ALIGNOF_PG_INT128_TYPE 16 355: #define MAXIMUM_ALIGNOF 8 374: #define PG_INT128_TYPE __int128
/include/c.h 507: /* 508: * 128-bit signed and unsigned integers 509: * There currently is only limited support for such types. 510: * E.g. 128bit literals and snprintf are not supported; but math is. 511: * Also, because we exclude such types when choosing MAXIMUM_ALIGNOF, 512: * it must be possible to coerce the compiler to allocate them on no 513: * more than MAXALIGN boundaries. 514: */ 515: #if defined(PG_INT128_TYPE) 516: #if defined(pg_attribute_aligned) || ALIGNOF_PG_INT128_TYPE <= MAXIMUM_ALIGNOF 517: #define HAVE_INT128 1 518: 519: typedef PG_INT128_TYPE int128 520: #if defined(pg_attribute_aligned) 521: pg_attribute_aligned(MAXIMUM_ALIGNOF) 522: #endif 523: ; 524: 525: typedef unsigned PG_INT128_TYPE uint128 526: #if defined(pg_attribute_aligned) 527: pg_attribute_aligned(MAXIMUM_ALIGNOF) 528: #endif 529: ; 530: 531: #endif 532: #endif 533: Hi. I am slightly confused by the int128 type. I thought the 128 bit integer means range type will be upto 2 ^ 127 - 1. Now just copy the above code and test the int128 range. int128 can only up to 9223372036854775807 (2 ^ 63 -1). also File: /home/jian/helloc/pg/pg_interval/include/pg_config_ext.h 6: /* Define to the name of a signed 64-bit integer type. */ 7: #define PG_INT64_TYPE long int I also thought that 64-bit means range up to 2 ^ 63 -1. Obviously I was wrong. So when we say "128 bit" what does it actually mean? -- I recommend David Deutsch's <<The Beginning of Infinity>> Jian
