#include <string.h>

#include <mruby.h>

#include <mruby/irep.h>

#include <mruby/debug.h>

static mrb_irep_debug_info_file*

get_file(mrb_irep_debug_info *info, uint32_t pc)

{

if (pc >= info->pc_count) { return NULL; }

/* get upper bound */

mrb_irep_debug_info_file **ret = info->files;

int32_t count = info->flen;

while (count > 0) {

int32_t step = count / 2;

mrb_irep_debug_info_file **it = ret + step;

if (!(pc < (*it)->start_pos)) {

ret = it + 1;

count -= step + 1;

}

else { count = step; }

}

--ret;

/* check returning file exists inside debug info */

mrb_assert(info->files <= ret && ret < (info->files + info->flen));

/* check pc is within the range of returning file */

mrb_assert((*ret)->start_pos <= pc &&

pc < (((ret + 1 - info->files) < info->flen)

? (*(ret+1))->start_pos : info->pc_count));

return *ret;

}

/*

* Calculates the number of bytes that `mrb_packed_int_encode` will write

* to store the given 32-bit unsigned integer `num`.

*/

size_t

mrb_packed_int_len(uint32_t num)

{

size_t llen = 0;

do {

llen++;

} while (num >>= 7);

return llen;

}

/*

* Encodes a 32-bit unsigned integer `num` into a variable-length packed format

* and writes it to the byte array `p`.

* The most significant bit of each byte is used as a continuation flag:

* - 1 indicates that more bytes follow.

* - 0 indicates the last byte.

* The lower 7 bits of each byte store parts of the number.

* Returns the number of bytes written to `p`.

*/

size_t

mrb_packed_int_encode(uint32_t num, uint8_t *p)

{

size_t llen = 0;

do {

uint8_t byte = num & 0x7f;

num >>= 7;

if (num != 0) byte |= 0x80;

*p++ = byte;

llen++;

} while (num != 0);

return llen;

}

/*

* Decodes a 32-bit unsigned integer from the variable-length packed format

* in the byte array `p`. It reads bytes until it finds one where the most

* significant bit is 0.

* If `newpos` is not NULL, it will be updated to point to the byte

* following the last byte read.

* Returns the decoded 32-bit unsigned integer.

*/

uint32_t

mrb_packed_int_decode(const uint8_t *p, const uint8_t **newpos)

{

size_t i = 0, shift = 0;

uint32_t n = 0;

do {

n |= ((uint32_t)(p[i] & 0x7f)) << shift;

i++;

shift += 7;

} while (shift < sizeof(uint32_t) * 8 && (p[i - 1] & 0x80));

if (newpos) *newpos = p + i;

return n;

}

static char const*

debug_get_filename(mrb_state *mrb, mrb_irep_debug_info_file* f)

{

if (f == NULL) return NULL;

return mrb_sym_name_len(mrb, f->filename_sym, NULL);

}

static int32_t

debug_get_line(mrb_state *mrb, mrb_irep_debug_info_file* f, uint32_t pc)

{

if (f == NULL) return -1;

switch (f->line_type) {

case mrb_debug_line_ary:

case mrb_debug_line_flat_map:

default:

break;

case mrb_debug_line_packed_map:

{

const uint8_t *p = f->lines.packed_map;

const uint8_t *pend = p + f->line_entry_count;

uint32_t pos = 0, line = 0;

while (p < pend) {

pos += mrb_packed_int_decode(p, &p);

uint32_t line_diff = mrb_packed_int_decode(p, &p);

if (pc < pos) break;

line += line_diff;

}

return line;

}

}

return -1;

}

/*

* Retrieves the filename for a given instruction pointer (pc)

* within a given mruby interpreter state (mrb) and mruby bytecode (irep).

* Returns NULL if the information is not available.

*/

MRB_API char const*

mrb_debug_get_filename(mrb_state *mrb, const mrb_irep *irep, uint32_t pc)

{

if (irep && pc < irep->ilen) {

if (!irep->debug_info) return NULL;

return debug_get_filename(mrb, get_file(irep->debug_info, pc));

}

return NULL;

}

/*

* Retrieves the line number for a given instruction pointer (pc)

* within a given mruby interpreter state (mrb) and mruby bytecode (irep).

* Returns -1 if the information is not available.

*/

MRB_API int32_t

mrb_debug_get_line(mrb_state *mrb, const mrb_irep *irep, uint32_t pc)

{

if (irep && pc < irep->ilen) {

if (!irep->debug_info) return -1;

return debug_get_line(mrb, get_file(irep->debug_info, pc), pc);

}

return -1;

}

/*

* Retrieves both the filename and line number for a given instruction pointer (pc)

* within a given mruby interpreter state (mrb) and mruby bytecode (irep).

* The line number is stored in the `lp` output parameter and the filename in the `fp` output parameter.

* Returns TRUE if the information is successfully retrieved, and FALSE otherwise.

* In case of failure, `lp` is set to -1 and `fp` is set to NULL.

*/

MRB_API mrb_bool

mrb_debug_get_position(mrb_state *mrb, const mrb_irep *irep, uint32_t pc, int32_t *lp, const char **fp)

{

if (irep && pc < irep->ilen && irep->debug_info) {

mrb_irep_debug_info_file *f = get_file(irep->debug_info, pc);

*lp = debug_get_line(mrb, f, pc);

if (*lp > 0) {

*fp = debug_get_filename(mrb, f);

if (*fp) return TRUE;

}

}

*lp = -1; *fp = NULL;

return FALSE;

}

/*

* Allocates and initializes a new `mrb_irep_debug_info` structure

* for a given mruby interpreter state (mrb) and mruby bytecode (irep).

* This function asserts that debug_info is not already allocated for the irep.

* Returns a pointer to the newly allocated `mrb_irep_debug_info` structure.

*/

MRB_API mrb_irep_debug_info*

mrb_debug_info_alloc(mrb_state *mrb, mrb_irep *irep)

{

static const mrb_irep_debug_info initial = { 0, 0, NULL };

mrb_assert(!irep->debug_info);

mrb_irep_debug_info *ret = (mrb_irep_debug_info*)mrb_malloc(mrb, sizeof(*ret));

*ret = initial;

irep->debug_info = ret;

return ret;

}

/*

* Appends a new file's debug information to an existing `mrb_irep_debug_info` structure `d`.

* It takes the mruby state `mrb`, the debug info structure `d`, the `filename`,

* an array of `lines` numbers, the `start_pos` (starting program counter for this file),

* and `end_pos` (ending program counter for this file).

* `filename` and `lines` must not be NULL.

* Returns a pointer to the newly created `mrb_irep_debug_info_file` structure,

* or NULL if `d` is NULL, `start_pos` equals `end_pos`, or if the filename is

* the same as the previously appended file.

*/

MRB_API mrb_irep_debug_info_file*

mrb_debug_info_append_file(mrb_state *mrb, mrb_irep_debug_info *d,

const char *filename, uint16_t *lines,

uint32_t start_pos, uint32_t end_pos)

{

if (!d) return NULL;

if (start_pos == end_pos) return NULL;

mrb_assert(filename);

mrb_assert(lines);

if (d->flen > 0) {

const char *fn = mrb_sym_name_len(mrb, d->files[d->flen - 1]->filename_sym, NULL);

if (strcmp(filename, fn) == 0)

return NULL;

}

mrb_irep_debug_info_file *f = (mrb_irep_debug_info_file*)mrb_malloc(mrb, sizeof(*f));

d->files = (mrb_irep_debug_info_file**)mrb_realloc(mrb, d->files, sizeof(mrb_irep_debug_info_file*) * (d->flen + 1));

d->files[d->flen++] = f;

uint32_t file_pc_count = end_pos - start_pos;

f->start_pos = start_pos;

d->pc_count = end_pos;

size_t fn_len = strlen(filename);

f->filename_sym = mrb_intern(mrb, filename, fn_len);

f->line_type = mrb_debug_line_packed_map;

f->lines.ptr = NULL;

uint16_t prev_line = 0;

uint32_t prev_pc = 0;

size_t packed_size = 0;

uint8_t *p;

for (uint32_t i = 0; i < file_pc_count; i++) {

if (lines[start_pos + i] == prev_line) continue;

packed_size += mrb_packed_int_len(start_pos+i-prev_pc);

prev_pc = start_pos+i;

packed_size += mrb_packed_int_len(lines[start_pos+i]-prev_line);

prev_line = lines[start_pos + i];

}

f->lines.packed_map = p = (uint8_t*)mrb_malloc(mrb, packed_size);

prev_line = 0; prev_pc = 0;

for (uint32_t i = 0; i < file_pc_count; i++) {

if (lines[start_pos + i] == prev_line) continue;

p += mrb_packed_int_encode(start_pos+i-prev_pc, p);

prev_pc = start_pos + i;

p += mrb_packed_int_encode(lines[start_pos + i]-prev_line, p);

prev_line = lines[start_pos + i];

}

f->line_entry_count = (uint32_t)packed_size;

return f;

}

/*

* Frees the memory allocated for an `mrb_irep_debug_info` structure `d`

* and all its associated data, including file information and line data.

* It takes the mruby state `mrb` and the debug info structure `d` to be freed.

* If `d` is NULL, the function does nothing.

*/

MRB_API void

mrb_debug_info_free(mrb_state *mrb, mrb_irep_debug_info *d)

{

if (!d) { return; }

if (d->files) {

for (uint32_t i = 0; i < d->flen; i++) {

if (d->files[i]) {

mrb_free(mrb, d->files[i]->lines.ptr);

mrb_free(mrb, d->files[i]);

}

}

mrb_free(mrb, d->files);

}

mrb_free(mrb, d);

}