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add io_seek
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@enricozb
enricozb committed Jun 10, 2024
1 parent 1c6ca2e commit 55a42b9
Showing 1 changed file with 150 additions and 39 deletions.
189 changes: 150 additions & 39 deletions src/run.c
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,14 @@ typedef struct Str {
char text_buf[256];
} Str;

// Readback: λ-Encoded list of bytes
typedef struct Bytes {
u32 len;
char *buf;
} Bytes;

#define MAX_BYTES 256

// IO Magic Number
#define IO_MAGIC_0 0xD0CA11
#define IO_MAGIC_1 0xFF1FF1
Expand Down Expand Up @@ -64,7 +72,7 @@ Ctr readback_ctr(Net* net, Book* book, Port port) {
return ctr;
}

// Converts a UTF-32 (truncated to 24 bits) string to a Port.
// Converts a Port into a UTF-32 (truncated to 24 bits) string.
// Since unicode scalars can fit in 21 bits, HVM's u24
// integers can contain any unicode scalar value.
// Encoding:
Expand All @@ -80,13 +88,9 @@ Str readback_str(Net* net, Book* book, Port port) {
// Normalizes the net
normalize(net, book);

//printf("reading str %s\n", show_port(peek(net, port)).x);

// Reads the λ-Encoded Ctr
Ctr ctr = readback_ctr(net, book, peek(net, port));

//printf("reading tag %d | len %d\n", ctr.tag, ctr.args_len);

// Reads string layer
switch (ctr.tag) {
case LIST_NIL: {
Expand All @@ -95,8 +99,7 @@ Str readback_str(Net* net, Book* book, Port port) {
case LIST_CONS: {
if (ctr.args_len != 2) break;
if (get_tag(ctr.args_buf[0]) != NUM) break;
if (str.text_len >= 256) { printf("ERROR: for now, HVM can only readback strings of length <256."); break; }
//printf("reading chr %d\n", get_u24(get_val(ctr.args_buf[0])));
if (str.text_len > 256) { printf("ERROR: for now, HVM can only readback strings of length <256."); break; }
str.text_buf[str.text_len++] = get_u24(get_val(ctr.args_buf[0]));
boot_redex(net, new_pair(ctr.args_buf[1], ROOT));
port = ROOT;
Expand All @@ -111,6 +114,45 @@ Str readback_str(Net* net, Book* book, Port port) {
return str;
}

// Converts a Port into a list of bytes.
// Encoding:
// - λt (t NIL)
// - λt (((t CONS) head) tail)
Bytes readback_bytes(Net* net, Book* book, Port port) {
// Result
Bytes bytes;
bytes.buf = malloc(sizeof(char) * MAX_BYTES);
bytes.len = 0;

// Readback loop
while (TRUE) {
// Normalizes the net
normalize(net, book);

// Reads the λ-Encoded Ctr
Ctr ctr = readback_ctr(net, book, peek(net, port));

// Reads string layer
switch (ctr.tag) {
case LIST_NIL: {
break;
}
case LIST_CONS: {
if (ctr.args_len != 2) break;
if (get_tag(ctr.args_buf[0]) != NUM) break;
if (bytes.len >= MAX_BYTES) { printf("ERROR: for now, HVM can only readback list of bytes of length <=%u.", MAX_BYTES); break; }
bytes.buf[bytes.len++] = get_u24(get_val(ctr.args_buf[0]));
boot_redex(net, new_pair(ctr.args_buf[1], ROOT));
port = ROOT;
continue;
}
}
break;
}

return bytes;
}

/// Returns a λ-Encoded Ctr for a NIL: λt (t NIL)
/// Should only be called within `inject_str`, as a previous call
/// to `get_resources` is expected.
Expand Down Expand Up @@ -180,6 +222,30 @@ Port inject_str(Net* net, Str *str) {
return port;
}

// Converts a list of bytes to a Port.
// Encoding:
// - λt (t NIL)
// - λt (((t CONS) head) tail)
Port inject_bytes(Net* net, Bytes *bytes) {
// Allocate all resources up front:
// - NIL needs 2 nodes & 1 var
// - CONS needs 4 nodes & 1 var
u32 len = bytes->len;
if (!get_resources(net, tm[0], 0, 2 + 4 * len, 1 + len)) {
printf("inject_str: failed to get resources\n");
return new_port(ERA, 0);
}

Port port = inject_nil(net);

for (u32 i = 0; i < len; i++) {
Port byte = new_port(NUM, new_u24(bytes->buf[len - i - 1]));
port = inject_cons(net, byte, port, i);
}

return port;
}

// Primitive IO Fns
// -----------------

Expand Down Expand Up @@ -213,47 +279,38 @@ FILE* readback_file(Port port) {
return fp;
}

// Reads a single char from `argm`.
Port io_read_char(Net* net, Book* book, Port argm) {
FILE* fp = readback_file(peek(net, argm));
if (fp == NULL) {
// Reads from a file a specified number of bytes.
// `argm` is a tuple of (file_descriptor, num_bytes).
Port io_read(Net* net, Book* book, Port argm) {
if (get_tag(peek(net, argm)) != CON) {
fprintf(stderr, "io_read: expected tuple, but got %u\n", get_tag(peek(net, argm)));
return new_port(ERA, 0);
}

/// Read a string.
Str str;

str.text_buf[0] = fgetc(fp);
str.text_buf[1] = 0;
str.text_len = 1;

return inject_str(net, &str);
}
Pair args = node_load(net, get_val(argm));

// Reads from `argm` at most 255 characters or until a newline is seen.
Port io_read_line(Net* net, Book* book, Port argm) {
FILE* fp = readback_file(peek(net, argm));
FILE* fp = readback_file(peek(net, get_fst(args)));
if (fp == NULL) {
fprintf(stderr, "io_read_line: invalid file descriptor\n");
return new_port(ERA, 0);
}

u32 num_bytes = get_u24(get_val(peek(net, get_snd(args))));

/// Read a string.
Str str;
Bytes bytes;
bytes.buf = malloc(sizeof(char) * num_bytes);
bytes.len = fread(bytes.buf, sizeof(char), num_bytes, fp);

if (fgets(str.text_buf, sizeof(str.text_buf), fp) == NULL) {
if ((bytes.len != num_bytes) && ferror(fp)) {
fprintf(stderr, "io_read_line: failed to read\n");
}
str.text_len = strlen(str.text_buf);

// Strip any trailing newline.
if (str.text_len > 0 && str.text_buf[str.text_len - 1] == '\n') {
str.text_buf[str.text_len] = 0;
str.text_len--;
}

// Convert it to a port.
return inject_str(net, &str);
Port ret = inject_bytes(net, &bytes);
free(bytes.buf);

return ret;
}

// Opens a file with the provided mode.
Expand All @@ -269,6 +326,8 @@ Port io_open_file(Net* net, Book* book, Port argm) {
Str name = readback_str(net, book, get_fst(args));
Str mode = readback_str(net, book, get_snd(args));

printf("opening file '%s' with mode '%s'\n", name.text_buf, mode.text_buf);

for (u32 fd = 3; fd < sizeof(FILE_POINTERS); fd++) {
if (FILE_POINTERS[fd] == NULL) {
FILE_POINTERS[fd] = fopen(name.text_buf, mode.text_buf);
Expand Down Expand Up @@ -311,17 +370,69 @@ Port io_write(Net* net, Book* book, Port argm) {

Pair args = node_load(net, get_val(argm));
FILE* fp = readback_file(peek(net, get_fst(args)));
Str str = readback_str(net, book, get_snd(args));
Bytes bytes = readback_bytes(net, book, get_snd(args));

if (fp == NULL) {
fprintf(stderr, "io_write: invalid file descriptor\n");
free(bytes.buf);

return new_port(ERA, 0);
}

if (fputs(str.text_buf, fp) == EOF) {
if (fwrite(bytes.buf, sizeof(char), bytes.len, fp) != bytes.len) {
fprintf(stderr, "io_write: failed to write\n");
}

free(bytes.buf);

return new_port(ERA, 0);
}

// Seeks to a position in a file.
// `argm` is a 3-tuple (CON fd (CON offset whence)), where
// - fd is a file descriptor
// - offset is a signed byte offset
// - whence is what that offset is relative to:
// - 0 (SEEK_SET): beginning of file
// - 1 (SEEK_CUR): current position of the file pointer
// - 2 (SEEK_END): end of the file
Port io_seek(Net* net, Book* book, Port argm) {
if (get_tag(peek(net, argm)) != CON) {
fprintf(stderr, "io_seek: expected first tuple, but got %u\n", get_tag(peek(net, argm)));
return new_port(ERA, 0);
}

Pair args1 = node_load(net, get_val(argm));
if (get_tag(peek(net, get_snd(args1))) != CON) {
fprintf(stderr, "io_seek: expected second tuple, but got %u\n", get_tag(peek(net, get_snd(args1))));
return new_port(ERA, 0);
}

Pair args2 = node_load(net, get_val(peek(net, get_snd(args1))));

FILE* fp = readback_file(peek(net, get_fst(args1)));
if (fp == NULL) {
fprintf(stderr, "io_write: invalid file descriptor\n");
return new_port(ERA, 0);
}

i32 offset = get_i24(get_val(peek(net, get_fst(args2))));
u32 whence = get_i24(get_val(peek(net, get_snd(args2))));

int cwhence;
switch (whence) {
case 0: cwhence = SEEK_SET; break;
case 1: cwhence = SEEK_CUR; break;
case 2: cwhence = SEEK_END; break;
default:
fprintf(stderr, "io_seek: invalid whence\n");
return new_port(ERA, 0);
}

if (fseek(fp, offset, cwhence) != 0) {
fprintf(stderr, "io_seek: failed to seek\n");
}

return new_port(ERA, 0);
}

Expand Down Expand Up @@ -365,11 +476,11 @@ Port io_sleep(Net* net, Book* book, Port argm) {
// -----------

void book_init(Book* book) {
book->ffns_buf[book->ffns_len++] = (FFn){"READ_CHAR", io_read_char};
book->ffns_buf[book->ffns_len++] = (FFn){"READ_LINE", io_read_line};
book->ffns_buf[book->ffns_len++] = (FFn){"OPEN_FILE", io_open_file};
book->ffns_buf[book->ffns_len++] = (FFn){"CLOSE_FILE", io_close_file};
book->ffns_buf[book->ffns_len++] = (FFn){"READ", io_read};
book->ffns_buf[book->ffns_len++] = (FFn){"OPEN", io_open_file};
book->ffns_buf[book->ffns_len++] = (FFn){"CLOSE", io_close_file};
book->ffns_buf[book->ffns_len++] = (FFn){"WRITE", io_write};
book->ffns_buf[book->ffns_len++] = (FFn){"SEEK", io_seek};
book->ffns_buf[book->ffns_len++] = (FFn){"GET_TIME", io_get_time};
book->ffns_buf[book->ffns_len++] = (FFn){"SLEEP", io_sleep};
}
Expand Down

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