ref: 9861f1a92b373a16939fd6f3c167e5dad9f253d3
dir: /sys/src/boot/pc/mem.h/
/* * Memory and machine-specific definitions. Used in C and assembler. */ /* * Sizes */ #define BI2BY 8 /* bits per byte */ #define BI2WD 32 /* bits per word */ #define BY2WD 4 /* bytes per word */ #define BY2PG 4096 /* bytes per page */ #define WD2PG (BY2PG/BY2WD) /* words per page */ #define PGSHIFT 12 /* log(BY2PG) */ #define PGROUND(s) (((s)+(BY2PG-1))&~(BY2PG-1)) /* * Fundamental addresses */ #define CONFADDR 0x1200 /* info passed from boot loader */ #define BIOSXCHG 0x6000 /* To exchange data with the BIOS */ #define SELGDT (0<<3) /* selector is in gdt */ #define SELLDT (1<<3) /* selector is in ldt */ #define SELECTOR(i, t, p) (((i)<<3) | (t) | (p)) /* * fields in segment descriptors */ #define SEGDATA (0x10<<8) /* data/stack segment */ #define SEGEXEC (0x18<<8) /* executable segment */ #define SEGTSS (0x9<<8) /* TSS segment */ #define SEGCG (0x0C<<8) /* call gate */ #define SEGIG (0x0E<<8) /* interrupt gate */ #define SEGTG (0x0F<<8) /* task gate */ #define SEGTYPE (0x1F<<8) #define SEGP (1<<15) /* segment present */ #define SEGPL(x) ((x)<<13) /* priority level */ #define SEGB (1<<22) /* granularity 1==4k (for expand-down) */ #define SEGG (1<<23) /* granularity 1==4k (for other) */ #define SEGE (1<<10) /* expand down */ #define SEGW (1<<9) /* writable (for data/stack) */ #define SEGR (1<<9) /* readable (for code) */ #define SEGD (1<<22) /* default 1==32bit (for code) */