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prf.c: remove arbitrary large stack buffer usage

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The on-stack work buffer occupies 201 bytes by default. Now that we've
made the code able to cope with virtually unlimited width and precision
values, we can reduce stack usage to its strict minimum i.e. 25 bytes.

This allows for some additional sprintf tests exercizing wide results.

Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
This commit is contained in:
Nicolas Pitre 2019-06-19 11:36:58 -04:00 • committed by Anas Nashif
commit f286eda6f0
2 changed files with 40 additions and 20 deletions
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33
tests/lib/sprintf/src/main.c
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@ -216,6 +216,39 @@ void test_sprintf_double(void)
zassert_true((strcmp(buffer, "1234.567890") == 0),
"sprintf(-1.0) - incorrect output '%s'\n", buffer);
/*
* With very large precision, the output differs significantly in
* terms of string even if not in terms of actual value depending
* on the library used and FPU implementation. However the length
* and decimal position should remain identical.
*/
var.d = 0x1p800;
sprintf(buffer, "%.140f", var.d);
zassert_true((strlen(buffer) == 382),
"sprintf(<large output>) - incorrect length %d\n",
strlen(buffer));
buffer[10] = 0; /* log facility doesn't support %.10s */
zassert_true((strcmp(buffer, "6668014432") == 0),
"sprintf(<large output>) - starts with \"%s\" "
"expected \"6668014432\"\n", buffer);
zassert_true((buffer[241] == '.'),
"sprintf(<large output>) - expected '.' got '%c'\n",
buffer[241]);
var.d = 0x1p-400;
sprintf(buffer, "% .380f", var.d);
zassert_true((strlen(buffer) == 383),
"sprintf(<large output>) - incorrect length %d\n",
strlen(buffer));
buffer[10] = 0; /* log facility doesn't support %.10s */
zassert_true((strcmp(buffer, " 0.0000000") == 0),
"sprintf(<large output>) - starts with \"%s\" "
"expected \" 0.0000000\"\n", buffer);
buffer[119 + 10] = 0; /* log facility doesn't support %.10s */
zassert_true((strcmp(buffer + 119, "0000387259") == 0),
"sprintf(<large output>) - got \"%s\" "
"while expecting \"0000387259\"\n", buffer + 119);
/*******************/
var.d = 1234.0;
sprintf(buffer, "%e", var.d);