From 95836f8439b9f1ca0b6ff20f56a03253aa9ba836 Mon Sep 17 00:00:00 2001 From: Damien George Date: Sun, 11 Jan 2015 22:27:30 +0000 Subject: [PATCH] py: Add MICROPY_QSTR_BYTES_IN_LEN config option, defaulting to 1. This new config option sets how many fixed-number-of-bytes to use to store the length of each qstr. Previously this was hard coded to 2, but, as per issue #1056, this is considered overkill since no-one needs identifiers longer than 255 bytes. With this patch the number of bytes for the length is configurable, and defaults to 1 byte. The configuration option filters through to the makeqstrdata.py script. Code size savings going from 2 to 1 byte: - unix x64 down by 592 bytes - stmhal down by 1148 bytes - bare-arm down by 284 bytes Also has RAM savings, and will be slightly more efficient in execution. --- py/makeqstrdata.py | 17 ++++++++++++++--- py/mpconfig.h | 7 +++++++ py/qstr.c | 32 +++++++++++++++++++------------- py/qstrdefs.h | 2 +- 4 files changed, 41 insertions(+), 17 deletions(-) diff --git a/py/makeqstrdata.py b/py/makeqstrdata.py index c8e998ed11..48fd9e09d4 100644 --- a/py/makeqstrdata.py +++ b/py/makeqstrdata.py @@ -73,16 +73,27 @@ def do_work(infiles): # add the qstr to the list, with order number to retain original order in file qstrs[ident] = (len(qstrs), ident, qstr) - # process the qstrs, printing out the generated C header file + # get config variables + cfg_bytes_len = int(qcfgs['BYTES_IN_LEN']) + cfg_max_len = 1 << (8 * cfg_bytes_len) + + # print out the starte of the generated C header file print('// This file was automatically generated by makeqstrdata.py') print('') + # add NULL qstr with no hash or data - print('QDEF(MP_QSTR_NULL, (const byte*)"\\x00\\x00\\x00\\x00" "")') + print('QDEF(MP_QSTR_NULL, (const byte*)"\\x00\\x00%s" "")' % ('\\x00' * cfg_bytes_len)) + + # go through each qstr and print it out for order, ident, qstr in sorted(qstrs.values(), key=lambda x: x[0]): qhash = compute_hash(qstr) qlen = len(qstr) qdata = qstr.replace('"', '\\"') - print('QDEF(MP_QSTR_%s, (const byte*)"\\x%02x\\x%02x\\x%02x\\x%02x" "%s")' % (ident, qhash & 0xff, (qhash >> 8) & 0xff, qlen & 0xff, (qlen >> 8) & 0xff, qdata)) + if qlen >= cfg_max_len: + print('qstr is too long:', qstr) + assert False + qlen_str = ('\\x%02x' * cfg_bytes_len) % tuple(qlen.to_bytes(cfg_bytes_len, 'little')) + print('QDEF(MP_QSTR_%s, (const byte*)"\\x%02x\\x%02x%s" "%s")' % (ident, qhash & 0xff, (qhash >> 8) & 0xff, qlen_str, qdata)) return True diff --git a/py/mpconfig.h b/py/mpconfig.h index dcc116daf2..541f7c75a5 100644 --- a/py/mpconfig.h +++ b/py/mpconfig.h @@ -112,6 +112,13 @@ #define MICROPY_MODULE_DICT_SIZE (1) #endif +// Number of bytes used to store qstr length +// Dictates hard limit on maximum Python identifier length, but 1 byte +// (limit of 255 bytes in an identifier) should be enough for everyone +#ifndef MICROPY_QSTR_BYTES_IN_LEN +#define MICROPY_QSTR_BYTES_IN_LEN (1) +#endif + /*****************************************************************************/ /* Micro Python emitters */ diff --git a/py/qstr.c b/py/qstr.c index bb31a08b39..c244738a5e 100644 --- a/py/qstr.c +++ b/py/qstr.c @@ -50,9 +50,17 @@ // - \0 terminated (for now, so they can be printed using printf) #define Q_GET_HASH(q) ((q)[0] | ((q)[1] << 8)) -#define Q_GET_ALLOC(q) (4 + Q_GET_LENGTH(q) + 1) -#define Q_GET_LENGTH(q) ((q)[2] | ((q)[3] << 8)) -#define Q_GET_DATA(q) ((q) + 4) +#define Q_GET_ALLOC(q) (2 + MICROPY_QSTR_BYTES_IN_LEN + Q_GET_LENGTH(q) + 1) +#define Q_GET_DATA(q) ((q) + 2 + MICROPY_QSTR_BYTES_IN_LEN) +#if MICROPY_QSTR_BYTES_IN_LEN == 1 + #define Q_GET_LENGTH(q) ((q)[2]) + #define Q_SET_LENGTH(q, len) do { (q)[2] = (len); } while (0) +#elif MICROPY_QSTR_BYTES_IN_LEN == 2 + #define Q_GET_LENGTH(q) ((q)[2] | ((q)[3] << 8)) + #define Q_SET_LENGTH(q, len) do { (q)[2] = (len); (q)[3] = (len) >> 8; } while (0) +#else + #error unimplemented qstr length decoding +#endif // this must match the equivalent function in makeqstrdata.py mp_uint_t qstr_compute_hash(const byte *data, mp_uint_t len) { @@ -143,23 +151,21 @@ qstr qstr_from_strn(const char *str, mp_uint_t len) { qstr q = qstr_find_strn(str, len); if (q == 0) { mp_uint_t hash = qstr_compute_hash((const byte*)str, len); - byte *q_ptr = m_new(byte, 4 + len + 1); + byte *q_ptr = m_new(byte, 2 + MICROPY_QSTR_BYTES_IN_LEN + len + 1); q_ptr[0] = hash; q_ptr[1] = hash >> 8; - q_ptr[2] = len; - q_ptr[3] = len >> 8; - memcpy(q_ptr + 4, str, len); - q_ptr[4 + len] = '\0'; + Q_SET_LENGTH(q_ptr, len); + memcpy(q_ptr + 2 + MICROPY_QSTR_BYTES_IN_LEN, str, len); + q_ptr[2 + MICROPY_QSTR_BYTES_IN_LEN + len] = '\0'; q = qstr_add(q_ptr); } return q; } byte *qstr_build_start(mp_uint_t len, byte **q_ptr) { - assert(len <= 65535); - *q_ptr = m_new(byte, 4 + len + 1); - (*q_ptr)[2] = len; - (*q_ptr)[3] = len >> 8; + assert(len < (1 << (8 * MICROPY_QSTR_BYTES_IN_LEN))); + *q_ptr = m_new(byte, 2 + MICROPY_QSTR_BYTES_IN_LEN + len + 1); + Q_SET_LENGTH(*q_ptr, len); return Q_GET_DATA(*q_ptr); } @@ -170,7 +176,7 @@ qstr qstr_build_end(byte *q_ptr) { mp_uint_t hash = qstr_compute_hash(Q_GET_DATA(q_ptr), len); q_ptr[0] = hash; q_ptr[1] = hash >> 8; - q_ptr[4 + len] = '\0'; + q_ptr[2 + MICROPY_QSTR_BYTES_IN_LEN + len] = '\0'; q = qstr_add(q_ptr); } else { m_del(byte, q_ptr, Q_GET_ALLOC(q_ptr)); diff --git a/py/qstrdefs.h b/py/qstrdefs.h index 514116b65d..71a523c2d6 100644 --- a/py/qstrdefs.h +++ b/py/qstrdefs.h @@ -30,7 +30,7 @@ // That is, they are in ROM and you can reference them simply as MP_QSTR_xxxx. // qstr configuration passed to makeqstrdata.py of the form QCFG(key, value) -//QCFG(somekey, somevalue) +QCFG(BYTES_IN_LEN, MICROPY_QSTR_BYTES_IN_LEN) Q() Q(*)