parse the %e, %E, %a, %A format specifiers instead of just ignoring t…

…hem. can't print them yet. (charlesnicholson#224)

* parse the %e, %E, %a, %A format specifiers instead of just ignoring them. can't print them yet.

* update readme

README.md

@@ -141,7 +141,9 @@ Like `printf`, `nanoprintf` expects a conversion specification string of the fol
 	* `x` / `X`: Unsigned hexadecimal integers
 	* `p`: Pointers
 	* `n`: Write the number of bytes written to the pointer vararg
-	* `f`/`F`: Floating-point values
+	* `f`/`F`: Floating-point decimal
+	* `e`/`E`: Floating-point scientific (unimplemented, prints decimal)
+	* `a`/`A`: Floating-point hex (unimplemented, prints decimal)
 	* `b`/`B`: Binary integers
 
 ## Floating Point
@@ -150,6 +152,8 @@ Floating point conversion is performed by extracting the value into 64:64 fixed-
 
 Because the float -> fixed code operates on the raw float value bits, no floating point operations are performed. This allows nanoprintf to efficiently format floats on soft-float architectures like Cortex-M0, and to function identically with or without optimizations like "fast math". Despite `nano` in the name, there's no way to do away with double entirely, since the C language standard says that floats are promoted to double any time they're passed into variadic argument lists. nanoprintf casts all doubles back down to floats before doing any conversions. No other single- or double- precision operations are performed.
 
+The `%e`/`%E` and `%a`/`%A` specifiers are parsed but not formatted. If used, the output will be identical to if `%f`/`%F` was used. Pull requests welcome! :)
+
 ## Limitations
 
 No wide-character support exists: the `%lc` and `%ls` fields require that the arg be converted to a char array as if by a call to [wcrtomb](http://man7.org/linux/man-pages/man3/wcrtomb.3.html). When locale and character set conversions get involved, it's hard to keep the name "nano". Accordingly, `%lc` and `%ls` behave like `%c` and `%s`, respectively.

nanoprintf.h

@@ -211,7 +211,9 @@ typedef enum {
   , NPF_FMT_SPEC_CONV_WRITEBACK   // 'n'
 #endif
 #if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
-  , NPF_FMT_SPEC_CONV_FLOAT_DECIMAL // 'f', 'F'
+  , NPF_FMT_SPEC_CONV_FLOAT_DEC   // 'f', 'F'
+  , NPF_FMT_SPEC_CONV_FLOAT_SCI   // 'e', 'E'
+  , NPF_FMT_SPEC_CONV_FLOAT_HEX   // 'a', 'A'
 #endif
 } npf_format_spec_conversion_t;
 
@@ -435,7 +437,21 @@ int npf_parse_format_spec(char const *format, npf_format_spec_t *out_spec) {
     case 'F':
       out_spec->case_adjust = 0;
     case 'f':
-      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_DECIMAL;
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_DEC;
+      if (out_spec->prec_opt == NPF_FMT_SPEC_OPT_NONE) { out_spec->prec = 6; }
+      break;
+
+    case 'E':
+      out_spec->case_adjust = 0;
+    case 'e':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_SCI;
+      if (out_spec->prec_opt == NPF_FMT_SPEC_OPT_NONE) { out_spec->prec = 6; }
+      break;
+
+    case 'A':
+      out_spec->case_adjust = 0;
+    case 'a':
+      out_spec->conv_spec = NPF_FMT_SPEC_CONV_FLOAT_HEX;
       if (out_spec->prec_opt == NPF_FMT_SPEC_OPT_NONE) { out_spec->prec = 6; }
       break;
 #endif
@@ -861,7 +877,9 @@ int npf_vpprintf(npf_putc pc, void *pc_ctx, char const *format, va_list args) {
 #endif
 
 #if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
-      case NPF_FMT_SPEC_CONV_FLOAT_DECIMAL: {
+      case NPF_FMT_SPEC_CONV_FLOAT_DEC:
+      case NPF_FMT_SPEC_CONV_FLOAT_SCI:
+      case NPF_FMT_SPEC_CONV_FLOAT_HEX: {
         float val;
         if (fs.length_modifier == NPF_FMT_SPEC_LEN_MOD_LONG_DOUBLE) {
           val = (float)va_arg(args, long double);
@@ -911,7 +929,7 @@ int npf_vpprintf(npf_putc pc, void *pc_ctx, char const *format, va_list args) {
 #if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
       if (!inf_or_nan) { // float precision is after the decimal point
         int const prec_start =
-          (fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DECIMAL) ? frac_chars : cbuf_len;
+          (fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC) ? frac_chars : cbuf_len;
         prec_pad = npf_max(0, fs.prec - prec_start);
       }
 #elif NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
@@ -925,7 +943,7 @@ int npf_vpprintf(npf_putc pc, void *pc_ctx, char const *format, va_list args) {
     if (need_0x) { field_pad -= 2; }
 
 #if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
-    if ((fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DECIMAL) && !fs.prec && !fs.alt_form) {
+    if ((fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC) && !fs.prec && !fs.alt_form) {
       ++field_pad; // 0-pad, no decimal point.
     }
 #endif
@@ -956,7 +974,7 @@ int npf_vpprintf(npf_putc pc, void *pc_ctx, char const *format, va_list args) {
     } else {
       if (sign_c) { NPF_PUTC(sign_c); }
 #if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
-      if (fs.conv_spec != NPF_FMT_SPEC_CONV_FLOAT_DECIMAL) {
+      if (fs.conv_spec != NPF_FMT_SPEC_CONV_FLOAT_DEC) {
 #endif
 
 #if NANOPRINTF_USE_PRECISION_FORMAT_SPECIFIERS == 1
@@ -980,7 +998,7 @@ int npf_vpprintf(npf_putc pc, void *pc_ctx, char const *format, va_list args) {
 
 #if NANOPRINTF_USE_FLOAT_FORMAT_SPECIFIERS == 1
       // real precision comes after the number.
-      if ((fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DECIMAL) && !inf_or_nan) {
+      if ((fs.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC) && !inf_or_nan) {
         while (prec_pad-- > 0) { NPF_PUTC('0'); }
       }
 #endif

tests/unit_parse_format_spec.cc

@@ -430,13 +430,37 @@ TEST_CASE("npf_parse_format_spec") {
 
     SUBCASE("f") {
       REQUIRE(npf_parse_format_spec("%f", &spec) == 2);
-      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DECIMAL);
+      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC);
       REQUIRE(spec.case_adjust == 'a' - 'A');
     }
 
     SUBCASE("F") {
       REQUIRE(npf_parse_format_spec("%F", &spec) == 2);
-      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DECIMAL);
+      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_DEC);
+      REQUIRE(spec.case_adjust == 0);
+    }
+
+    SUBCASE("e") {
+      REQUIRE(npf_parse_format_spec("%e", &spec) == 2);
+      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_SCI);
+      REQUIRE(spec.case_adjust == 'a' - 'A');
+    }
+
+    SUBCASE("E") {
+      REQUIRE(npf_parse_format_spec("%E", &spec) == 2);
+      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_SCI);
+      REQUIRE(spec.case_adjust == 0);
+    }
+
+    SUBCASE("a") {
+      REQUIRE(npf_parse_format_spec("%a", &spec) == 2);
+      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_HEX);
+      REQUIRE(spec.case_adjust == 'a' - 'A');
+    }
+
+    SUBCASE("A") {
+      REQUIRE(npf_parse_format_spec("%A", &spec) == 2);
+      REQUIRE(spec.conv_spec == NPF_FMT_SPEC_CONV_FLOAT_HEX);
       REQUIRE(spec.case_adjust == 0);
     }