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Use 32b loads to set print strings #7545

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merged 4 commits into from
Oct 16, 2020
Merged

Use 32b loads to set print strings #7545

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46b221d
Use 32b loads to set print strings
earlephilhower Aug 23, 2020
88c9452
Merge branch 'master' into bootmin
earlephilhower Sep 2, 2020
268f29a
Merge branch 'master' of https://github.com/esp8266/Arduino into bootmin
earlephilhower Oct 15, 2020
14c5303
Merge branch 'master' into bootmin
earlephilhower Oct 16, 2020
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37 changes: 23 additions & 14 deletions bootloaders/eboot/eboot.c
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Original file line number Diff line number Diff line change
Expand Up @@ -21,20 +21,20 @@ extern unsigned char _gzip_dict;
extern void ets_wdt_enable(void);
extern void ets_wdt_disable(void);

// Converts bit of a string into a uint32
#define S(a,b,c,d) ( (((uint32_t)a) & 0xff) | (((uint32_t)b) << 8) | (((uint32_t)c) << 16) | (((uint32_t)d)<<24) )

int print_version(const uint32_t flash_addr)
{
uint32_t ver;
if (SPIRead(flash_addr + APP_START_OFFSET + sizeof(image_header_t) + sizeof(section_header_t), &ver, sizeof(ver))) {
return 1;
}
char fmt[7];
fmt[0] = 'v';
fmt[1] = '%';
fmt[2] = '0';
fmt[3] = '8';
fmt[4] = 'x';
fmt[5] = '\n';
fmt[6] = 0;
// We don't have BSS and can't print from flash, so build up string
// 4 chars at a time. Smaller code than byte-wise assignment.
uint32_t fmt[2];
fmt[0] = S('v', '%', '0', '8');
fmt[1] = S('x', '\n', 0, 0);
ets_printf((const char*) fmt, ver);
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more readable solution I guess is:

#define TINYSTR(str) [__builtin_strlen(str) + 1] = str
#define TINYCHARS(chars) [__builtin_strlen(chars)] = chars

and then,

    const char fmt TINYSTR("v%08x\n");
    ets_printf(fmt, ver);

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OMG, greater then 4 bytes string literals will be placed into RODATA (and memcpy will copy them)...

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Sorry,

#define S(str) ((uint32_t)(str"\0\0\0")[0] | ((uint32_t)(str"\0\0\0")[1] << 8) | ((uint32_t)(str"\0\0\0")[2] << 16) | ((uint32_t)(str"\0\0\0")[3] << 24))

and

    const uint32_t fmt[] = { S("v%08"), S("x\n") };
    ets_printf(fmt, ver);

are OK (now placed into .text).

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Yeah, there aren't any really good solutions. We don't allow RODATA because we don't have the C init stuff in the bootloader. Can't use PSTR because ets_printf can't handle PROGMEM byte accesses. GCC's multichar literal puts things in the wrong order for strings (endian issue). So we end up with either a 4-param or 1-param marco w/array indexing.

Honestly, I like the existing setup more than the string 4-chars because with the current macro, if you accidentally put in a >4 char element it will error (while the string[index] will silently allow it).

But, your idea to make it a const array to get in .text, that's pretty cool. Let me see what it does to the size, might buy 4-8 bytes per instance...

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Argh, looks like that's not going to work. I see .rodata appear when I do const uint32_t s={S(),S()}; Back where we were...

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@earlephilhower earlephilhower Aug 24, 2020 •
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Also, anyway, the string needs to be in RAM since it will be byte accessed. So if it was reduced to just a pointer to ICACHE (where eboot lives)/PROGMEM it would end up SEGV'ing. Has to be a copy to RAM step no matter what.

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Haha, get to be quite weird definition...
( #include <assert.h> needed )

#define S(x, str) \
    do { \
        const unsigned int l = (__builtin_strlen(str) + 1 + 3) / 4; \
        static_assert(sizeof(x) / sizeof(*x) == l); \
        unsigned int i = 0; \
        while(i < l) \
            x[i] = ((uint32_t)(str"\0\0\0")[i * 4 + 0] | ((uint32_t)(str"\0\0\0")[i * 4 + 1] << 8) | ((uint32_t)(str"\0\0\0")[i * 4 + 2] << 16) | ((uint32_t)(str"\0\0\0")[i * 4 + 3] << 24)), ++i; \
    } while(0)

and

void test(void) {
    uint32_t fmt[3];
    S(fmt, "foo bar baz");

    extern int write(const void*);
    write((const char*)fmt);
}

emits the below (good result)

	.file	"test.c"
	.text
	.literal_position
	.literal .LC0, 544173926
	.literal .LC1, 544366946
	.literal .LC2, 8020322
	.align	4
	.global	test
	.type	test, @function
test:
	l32r	a2, .LC0
	addi	sp, sp, -32
	s32i.n	a2, sp, 0
	l32r	a2, .LC1
	s32i.n	a0, sp, 28
	s32i.n	a2, sp, 4
	l32r	a2, .LC2
	s32i.n	a2, sp, 8
	mov.n	a2, sp
	call0	write
	l32i.n	a0, sp, 28
	addi	sp, sp, 32
	ret.n
	.size	test, .-test
	.ident	"GCC: (GNU) 10.1.0"

but this

void test(void) {
    uint32_t fmt[4];
    S(fmt, "foo bar baz ");  /* 1 whitespace appended */

    extern int write(const void*);
    write((const char*)fmt);
}

emits bad...

	.file	"test.c"
	.text
	.section	.rodata
.LC0:
	.string	"foo bar baz "
	.string	""
	.string	""
	.string	""
	.text
	.literal_position
	.literal .LC1, .LC0
	.align	4
	.global	test
	.type	test, @function
test:
	addi	sp, sp, -32
	l32r	a3, .LC1
	s32i.n	a0, sp, 28
	movi.n	a4, 0
.L2:
	l8ui	a2, a3, 1
	l8ui	a5, a3, 2
	slli	a2, a2, 8
	slli	a5, a5, 16
	or	a2, a2, a5
	l8ui	a5, a3, 0
	add.n	a6, sp, a4
	or	a2, a2, a5
	l8ui	a5, a3, 3
	addi.n	a4, a4, 4
	slli	a5, a5, 24
	or	a2, a2, a5
	s32i.n	a2, a6, 0
	addi.n	a3, a3, 4
	bnei	a4, 16, .L2
	mov.n	a2, sp
	call0	write
	l32i.n	a0, sp, 28
	addi	sp, sp, 32
	ret.n
	.size	test, .-test
	.ident	"GCC: (GNU) 10.1.0"

return 0;
}
Expand Down Expand Up @@ -222,26 +222,32 @@ int main()
}

if (cmd.action == ACTION_COPY_RAW) {
ets_putc('c'); ets_putc('p'); ets_putc(':');
uint32_t cp = S('c', 'p', ':', 0);
ets_printf((const char *)cp);

ets_wdt_disable();
res = copy_raw(cmd.args[0], cmd.args[1], cmd.args[2], false);
ets_wdt_enable();

ets_putc('0'+res); ets_putc('\n');
cp = S('0' + res, '\n', 0, 0 );
ets_printf((const char *)cp);
#if 0
//devyte: this verify step below (cmp:) only works when the end of copy operation above does not overwrite the
//beginning of the image in the empty area, see #7458. Disabling for now.
//TODO: replace the below verify with hash type, crc, or similar.
// Verify the copy
ets_putc('c'); ets_putc('m'); ets_putc('p'); ets_putc(':');
uint32_t v[2];
v[0] = S('c', 'm', 'p', ':');
v[1] = 0;
ets_printf(const char *)v);
if (res == 0) {
ets_wdt_disable();
res = copy_raw(cmd.args[0], cmd.args[1], cmd.args[2], true);
ets_wdt_enable();
}

ets_putc('0'+res); ets_putc('\n');
cp = S('0' + res, '\n', 0, 0 );
ets_printf((const char *)cp);
#endif
if (res == 0) {
cmd.action = ACTION_LOAD_APP;
Expand All @@ -256,8 +262,11 @@ int main()
if (cmd.action == ACTION_LOAD_APP) {
ets_putc('l'); ets_putc('d'); ets_putc('\n');
res = load_app_from_flash_raw(cmd.args[0]);
//we will get to this only on load fail
ets_putc('e'); ets_putc(':'); ets_putc('0'+res); ets_putc('\n');
// We will get to this only on load fail
uint32_t e[2];
e[0] = S('e', ':', '0' + res, '\n' );
e[1] = 0;
ets_printf((const char*)e);
}

if (res) {
Expand Down
Binary file modified bootloaders/eboot/eboot.elf
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