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Add read/write map functions to vm_segment

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This commit is contained in:
Peter Evans 2017-12-12 14:31:44 -06:00
parent daab8a7f58
commit b36bb78a12
1 changed files with 32 additions and 2 deletions
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34
include/vm_segment.h
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@ -4,6 +4,24 @@
#include "vm_bits.h"
#include "log.h"
/*
* Here we make a forward declaration of the vm_segment. (We also
* typedef that struct as `vm_segment`, so we don't have to say `struct
* vm_segment` everywhere.)
*/
struct vm_segment;
typedef struct vm_segment vm_segment;
/*
* The above forward declaration allows us to define the types for the
* read and write function signatures that we intend to use in the
* _definition_ of the vm_segment struct.
*
* C is fun! Don't let anyone tell you otherwise.
*/
typedef vm_8bit (*vm_segment_read_fn)(vm_segment *, size_t);
typedef void (*vm_segment_write_fn)(vm_segment *, size_t, vm_8bit);
/*
* The bounds check is just some inline code to try and cut down on the
* cost of it.
@ -11,7 +29,8 @@
#define vm_segment_bounds_check(segment, index) \
(index == index % segment->size)
typedef struct {
struct vm_segment {
/*
* The size of our memory segment. This is used for bounds checking.
*/
@ -21,7 +40,18 @@ typedef struct {
* This is the actual chunk of memory we allocate.
*/
vm_8bit *memory;
} vm_segment;
/*
* These are memory maps; if we have defined a non-NULL entry for a
* given address in read_table, then that is a function we will use
* to return the value for that address. Likewise, if we have a
* non-NULL entry in write_table, we will use that to "set" the
* value. As you may guess, these should conventionally be the
* exact size indicated by the size field.
*/
vm_segment_read_fn *read_table;
vm_segment_write_fn *write_table;
};
extern int vm_segment_copy(vm_segment *, vm_segment *, size_t, size_t, size_t);
extern vm_segment *vm_segment_create(size_t);