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65 lines
2.0 KiB
C
65 lines
2.0 KiB
C
#ifndef _VM_SEGMENT_H_
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#define _VM_SEGMENT_H_
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#include "vm_bits.h"
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#include "log.h"
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/*
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* Here we make a forward declaration of the vm_segment. (We also
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* typedef that struct as `vm_segment`, so we don't have to say `struct
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* vm_segment` everywhere.)
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*/
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struct vm_segment;
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typedef struct vm_segment vm_segment;
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/*
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* The above forward declaration allows us to define the types for the
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* read and write function signatures that we intend to use in the
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* _definition_ of the vm_segment struct.
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*
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* C is fun! Don't let anyone tell you otherwise.
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*/
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typedef vm_8bit (*vm_segment_read_fn)(vm_segment *, size_t);
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typedef void (*vm_segment_write_fn)(vm_segment *, size_t, vm_8bit);
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/*
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* The bounds check is just some inline code to try and cut down on the
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* cost of it.
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*/
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#define vm_segment_bounds_check(segment, index) \
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(index == index % segment->size)
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struct vm_segment {
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/*
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* The size of our memory segment. This is used for bounds checking.
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*/
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size_t size;
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/*
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* This is the actual chunk of memory we allocate.
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*/
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vm_8bit *memory;
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/*
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* These are memory maps; if we have defined a non-NULL entry for a
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* given address in read_table, then that is a function we will use
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* to return the value for that address. Likewise, if we have a
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* non-NULL entry in write_table, we will use that to "set" the
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* value. As you may guess, these should conventionally be the
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* exact size indicated by the size field.
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*/
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vm_segment_read_fn *read_table;
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vm_segment_write_fn *write_table;
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};
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extern int vm_segment_copy(vm_segment *, vm_segment *, size_t, size_t, size_t);
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extern int vm_segment_read_map(vm_segment *, size_t, vm_segment_read_fn);
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extern int vm_segment_set(vm_segment *, size_t, vm_8bit);
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extern int vm_segment_write_map(vm_segment *, size_t, vm_segment_write_fn);
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extern vm_8bit vm_segment_get(vm_segment *, size_t);
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extern vm_segment *vm_segment_create(size_t);
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extern void vm_segment_free(vm_segment *);
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#endif
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