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VMEM file: use file object directly instead of RAM buffer #78

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9ebc7a5
VMEM file: use file object directly instead of RAM buffer
jeanbaptistelab May 1, 2026
6cd64a9
Add separate type/implementation for fixed VADDR VMEM file objects, p…
jeanbaptistelab May 4, 2026
c854d3e
Remove leftover "&", revert "__alignof__(vmem_t)" in VMEM_DEFINE_FILE…
jeanbaptistelab May 4, 2026
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17 changes: 11 additions & 6 deletions include/vmem/vmem_file.h
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Original file line number Diff line number Diff line change
Expand Up @@ -32,9 +32,16 @@ typedef struct {
FILE * stream;
} vmem_file_driver_t;

typedef struct {
const char * filename;
FILE * stream;
} vmem_file_vaddr_driver_t;

void vmem_file_init(const vmem_t * vmem);
void vmem_file_read(const vmem_t * vmem, uint64_t addr, void * dataout, uint32_t len);
void vmem_file_write(const vmem_t * vmem, uint64_t addr, const void * datain, uint32_t len);
void vmem_file_vaddr_read(const vmem_t * vmem, uint64_t addr, void * dataout, uint32_t len);
void vmem_file_vaddr_write(const vmem_t * vmem, uint64_t addr, const void * datain, uint32_t len);

#define VMEM_DEFINE_FILE(name_in, strname, filename_in, size_in) \
uint8_t vmem_##name_in##_buf[size_in] = {}; \
Expand All @@ -57,20 +64,18 @@ void vmem_file_write(const vmem_t * vmem, uint64_t addr, const void * datain, ui
};

#define VMEM_DEFINE_FILE_VADDR(name_in, strname, filename_in, size_in, fixed_vaddr) \
uint8_t vmem_##name_in##_buf[size_in] = {}; \
static vmem_file_driver_t vmem_##name_in##_driver = { \
.physaddr = vmem_##name_in##_buf, \
static vmem_file_vaddr_driver_t vmem_##name_in##_driver = { \
.filename = filename_in, \
}; \
__attribute__((section("vmem"))) \
__attribute__((aligned(8))) \
__attribute__((aligned(__alignof__(vmem_t)))) \
__attribute__((used)) \
const vmem_t vmem_##name_in = { \
.type = VMEM_TYPE_FILE, \
.name = strname, \
.size = size_in, \
.read = vmem_file_read, \
.write = vmem_file_write, \
.read = vmem_file_vaddr_read, \
.write = vmem_file_vaddr_write, \
.driver = &vmem_##name_in##_driver, \
.vaddr = (uint64_t)fixed_vaddr, \
.ack_with_pull = 1, \
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40 changes: 39 additions & 1 deletion src/vmem/vmem_file.c
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Original file line number Diff line number Diff line change
Expand Up @@ -44,7 +44,45 @@ void vmem_file_write(const vmem_t * vmem, uint64_t addr, const void * datain, ui
/* Flush back to file */
int res = fseek(driver->stream, addr, SEEK_SET);
(void)res;
int written = fwrite((char *) driver->physaddr + addr, len, 1, driver->stream);
int written = fwrite((void*)((intptr_t)driver->physaddr + addr), len, 1, driver->stream);
fflush(driver->stream);
(void) written;
}
}

static void vmem_file_vaddr_init(const vmem_t * vmem) {
vmem_file_driver_t *driver = (vmem_file_driver_t *) vmem->driver;
if(driver->stream == NULL) {
/* Open file for reading/writing, creating it if it doesn't exist */
int fd = open(driver->filename, O_RDWR|O_CREAT, S_IRUSR|S_IWUSR);
if (fd != -1) {
driver->stream = fdopen(fd, "r+");
}
if(!driver->stream) {
printf("\nWARNING: vmem[%s]: permission/path issues for associated filename: \"%s\"\n", vmem->name, driver->filename);
}
}
}

void vmem_file_vaddr_read(const vmem_t * vmem, uint64_t addr, void * dataout, uint32_t len) {
vmem_file_driver_t *driver = (vmem_file_driver_t *) vmem->driver;
vmem_file_vaddr_init(vmem);
if(driver->stream ) {
int res = fseek(driver->stream, addr, SEEK_SET);
(void)res;
res = fread(dataout, len, 1, driver->stream);
(void)res;
}
}

void vmem_file_vaddr_write(const vmem_t * vmem, uint64_t addr, const void * datain, uint32_t len) {
vmem_file_driver_t *driver = (vmem_file_driver_t *) vmem->driver;
vmem_file_vaddr_init(vmem);
if(driver->stream ) {
/* Flush back to file */
int res = fseek(driver->stream, addr, SEEK_SET);
(void)res;
int written = fwrite(datain, len, 1, driver->stream);
fflush(driver->stream);
(void) written;
}
Expand Down