gmio_core/internal: add gmio_parse_float32()

src/gmio_core/internal/string_parse.h

@@ -25,6 +25,8 @@
  *  To be used with API below.
  *  It allows to iterate over a stream (until end is reached) as if it was a
  *  string.
+ *
+ *  TODO: rename to gmio_string_stream
  */
 struct gmio_string_stream_fwd_iterator
 {
@@ -34,8 +36,7 @@ struct gmio_string_stream_fwd_iterator
     const char* strbuff_ptr_at;  /*!< Position indicator in buffer */
 
     void* cookie;
-    void (*func_stream_read_hook)(
-            void* cookie, const gmio_string_t* str_buffer);
+    void (*func_stream_read_hook)(void* cookie, const gmio_string_t* strbuff);
 };
 
 typedef struct gmio_string_stream_fwd_iterator
@@ -89,6 +90,10 @@ gmio_bool_t gmio_checked_next_chars(
         gmio_string_stream_fwd_iterator_t* it, const char* str);
 #endif
 
+/*! Parses float from string iterator \p it */
+GMIO_INLINE gmio_float32_t gmio_parse_float32(
+        gmio_string_stream_fwd_iterator_t* it);
+
 /*! Converts C string \p str to float
  *
  *  \retval 0  On success
@@ -109,6 +114,7 @@ GMIO_INLINE gmio_float32_t gmio_to_float32(const char* str);
 #include "string_utils.h"
 #ifdef GMIO_STRINGPARSE_USE_FAST_ATOF
 #  include "fast_atof.h"
+#  include "string_parse_fast_atof.h"
 #endif
 
 #include <errno.h>
@@ -148,7 +154,6 @@ gmio_string_stream_fwd_iterator_t* gmio_move_next_char(
     return it;
 }
 
-
 const char* gmio_skip_spaces(
         gmio_string_stream_fwd_iterator_t* it)
 {
@@ -198,4 +203,16 @@ gmio_float32_t gmio_to_float32(const char* str)
 #endif
 }
 
+gmio_float32_t gmio_parse_float32(gmio_string_stream_fwd_iterator_t* it)
+{
+#if defined(GMIO_STRINGPARSE_USE_FAST_ATOF)
+    return gmio_fast_atof(it);
+#else
+    char strbuff_ptr[64];
+    gmio_string_t strbuff = { &strbuff_ptr[0], 0, sizeof(strbuff_ptr) };
+    gmio_eat_word(it, &strbuff);
+    return (gmio_float32_t)atof(strbuff_ptr);
+#endif
+}
+
 #endif /* GMIO_INTERNAL_STRING_PARSE_H */

src/gmio_core/internal/string_parse_fast_atof.h

@@ -0,0 +1,112 @@
+/* Copyright (C) 2002-2012 Nikolaus Gebhardt
+ * This file is part of the "Irrlicht Engine" and the "irrXML" project.
+ * For conditions of distribution and use, see copyright notice in irrlicht.h
+ * and irrXML.h
+ */
+
+/* Adapted to ISO-C90 */
+
+#ifndef GMIO_INTERNAL_STRING_PARSE_FAST_ATOF_H
+#define GMIO_INTERNAL_STRING_PARSE_FAST_ATOF_H
+
+#include "fast_atof.h"
+#include "string_parse.h"
+
+GMIO_INLINE uint32_t gmio_strtoul10(gmio_string_stream_fwd_iterator_t* it)
+{
+    unsigned int value = 0;
+    const char* in = gmio_current_char(it);
+    for (; in != NULL && gmio_ascii_isdigit(*in); in = gmio_next_char(it))
+        value = (value * 10) + (*in - '0');
+    return value;
+}
+
+GMIO_INLINE int32_t gmio_strtol10(gmio_string_stream_fwd_iterator_t* it)
+{
+    const char* in = gmio_current_char(it);
+    const gmio_bool_t inv = (*in == '-');
+    int value = 0;
+    if (inv || *in == '+')
+        in = gmio_next_char(it);
+
+    value = gmio_strtoul10(it);
+    if (inv)
+        value = -value;
+    return value;
+}
+
+struct gmio_strtof10_result
+{
+    float val;
+    unsigned char_diff;
+};
+typedef struct gmio_strtof10_result gmio_strtof10_result_t;
+
+GMIO_INLINE gmio_strtof10_result_t gmio_strtof10(
+        gmio_string_stream_fwd_iterator_t* it)
+{
+    const char* in = gmio_current_char(it);
+    const uint32_t MAX_SAFE_U32_VALUE = UINT_MAX / 10 - 10;
+    uint32_t int_val = 0;
+    float float_val = 0.f;
+    unsigned char_diff = 0;
+    gmio_strtof10_result_t result;
+
+    /* Use integer arithmetic for as long as possible, for speed and
+     * precision */
+    for (;
+         in != NULL && gmio_ascii_isdigit(*in) && int_val < MAX_SAFE_U32_VALUE;
+         in = gmio_next_char(it))
+    {
+        int_val = (int_val * 10) + (*in - '0');
+        ++char_diff;
+    }
+    float_val = (float)int_val;
+    /* If there are any digits left to parse, then we need to use floating point
+     * arithmetic from here */
+    for (;
+         in != NULL && gmio_ascii_isdigit(*in) && float_val <= FLT_MAX;
+         in = gmio_next_char(it))
+    {
+        float_val = (float_val * 10) + (*in - '0');
+        ++char_diff;
+    }
+    result.val = float_val;
+    result.char_diff = char_diff;
+    return result;
+}
+
+GMIO_INLINE float gmio_fast_atof(gmio_string_stream_fwd_iterator_t* it)
+{
+    const char* in = gmio_current_char(it);
+    const gmio_bool_t negative = ('-' == *in);
+    float value = 0.f;
+
+    /* Please run the regression test when making any modifications to this
+     * function. */
+    if (negative || ('+' == *in))
+        in = gmio_next_char(it);
+    value = gmio_strtof10(it).val;
+    in = gmio_current_char(it);
+    if (is_local_decimal_point(*in)) {
+        const gmio_strtof10_result_t decimal =
+                gmio_strtof10(gmio_move_next_char(it));
+        value += decimal.val * fast_atof_table[decimal.char_diff];
+        in = gmio_current_char(it);
+    }
+    if (in != NULL && ('e' == *in || 'E' == *in)) {
+        in = gmio_next_char(it);
+        /* Assume that the exponent is a whole number.
+         * strtol10() will deal with both + and - signs,
+         * but calculate as float to prevent overflow at FLT_MAX */
+        value *=
+#ifdef GMIO_HAVE_POWF_FUNC
+                powf(10.f, (float)gmio_strtol10(it));
+#else
+                (float)pow(10., (double)gmio_strtol10(it));
+#endif
+    }
+    return negative ? -value : value;
+}
+
+#endif /* GMIO_INTERNAL_STRING_PARSE_FAST_ATOF_H */

tests/main_test_core.c

@@ -23,6 +23,7 @@ const char* test_core__stream();
 const char* test_internal__byte_swap();
 const char* test_internal__byte_codec();
 const char* test_internal__fast_atof();
+const char* test_internal__gmio_fast_atof();
 const char* test_internal__safe_cast();
 const char* test_internal__string_parse();
 const char* test_internal__string_utils();
@@ -43,6 +44,7 @@ const char* all_tests()
     UTEST_RUN(test_internal__byte_swap);
     UTEST_RUN(test_internal__byte_codec);
     UTEST_RUN(test_internal__fast_atof);
+    UTEST_RUN(test_internal__gmio_fast_atof);
     UTEST_RUN(test_internal__safe_cast);
     UTEST_RUN(test_internal__string_parse);
     UTEST_RUN(test_internal__string_utils);

tests/test_core_internal.c

@@ -62,7 +62,7 @@ const char* test_internal__byte_codec()
 
 static gmio_bool_t gmio_test_calculation_atof(const char* value_str)
 {
-    const gmio_float32_t fast_value = fast_atof(value_str, NULL);
+    const gmio_float32_t fast_value = fast_atof(value_str);
     const gmio_float32_t std_value = (gmio_float32_t)strtod(value_str, NULL);
     const gmio_bool_t accurate =
             gmio_float32_equals_by_ulp(fast_value, std_value, 1);
@@ -124,6 +124,35 @@ const char* test_internal__fast_atof()
     return NULL;
 }
 
+const char* test_internal__gmio_fast_atof()
+{
+    const char fstr[] = "1234.567E05";
+    const float f1 = fast_atof(fstr);
+
+    {
+        char strbuff[2048] = {0};
+        gmio_string_stream_fwd_iterator_t it = {0};
+        gmio_stream_buffer_t streambuff = {0};
+        gmio_stream_t stream = {0};
+        float f2;
+
+        streambuff.readonly_ptr = &fstr[0];
+        streambuff.len = sizeof(fstr) - 1;
+        gmio_stream_set_buffer(&stream, &streambuff);
+
+        it.stream = &stream;
+        it.strbuff.ptr = &strbuff[0];
+        it.strbuff.max_len = sizeof(strbuff) - 1;
+        gmio_string_stream_fwd_iterator_init(&it);
+
+        f2 = gmio_fast_atof(&it);
+
+        UTEST_ASSERT(gmio_float32_equals_by_ulp(f1, f2, 1));
+    }
+
+    return NULL;
+}
+
 const char* test_internal__safe_cast()
 {
 #if GMIO_TARGET_ARCH_BIT_SIZE > 32