1 files changed, 97 insertions, 0 deletions
diff --git a/src/u8c/u8.h.d/u8enc.c b/src/u8c/u8.h.d/u8enc.c
new file mode 100644
index 0000000..f3f3570
--- /dev/null
+++ b/src/u8c/u8.h.d/u8enc.c
@@ -0,0 +1,97 @@
+/*
+	Copyright 2021 Gabriel Jensen
+
+	This file is part of u8c.
+
+	u8c is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
+
+	u8c is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+
+	See the	GNU Affero General Public License for more details.
+
+	You should have received a copy of the GNU Affero General Public License along with u8c.
+
+	If not, see <https://www.gnu.org/licenses/>.
+*/
+# include <assert.h>
+# include <stdbool.h>
+# include <stddef.h>
+# include <stdint.h>
+# include <u8c/SIZE_C.h>
+# include <u8c/err.h>
+# include <u8c/u32.h>
+# include <u8c/u8.h>
+# include <uchar.h>
+bool u8c_u8enc(size_t * const _sz,unsigned char const * * const _out,char32_t const * const _in) {
+	assert(_out != NULL);
+	assert(_in != NULL);
+	size_t insz  = SIZE_C(0x0); /* Size of input array (bytes). */
+	size_t outsz = SIZE_C(0x0); /* Size of output array /bytes). */
+	for(register size_t n = SIZE_C(0x0);n <= SIZE_MAX;n += SIZE_C(0x1)) { /* First pass: get size of input array, and determine size of output array. */
+		register char32_t const tmp = _in[n];
+		if(tmp > u8c_u32max) { /* Codepoint out of range. */
+			u8c_seterr(U"u8c_u8enc: Codepoint out of range (too big).",u8c_errtyp_u32oor);
+			return true;
+		}
+		if(tmp >= UINT32_C(0x10000)) { /* 4 bytes. */
+			outsz += SIZE_C(0x4);
+			continue;
+		}
+		if(tmp >= UINT32_C(0x800)) { /* 3 bytes. */
+			outsz += SIZE_C(0x3);
+			continue;
+		}
+		if(tmp >= UINT32_C(0x80)) { /* 2 bytes. */
+			outsz += SIZE_C(0x2);
+			continue;
+		}
+		/* 1 byte. */
+		outsz += SIZE_C(0x1);
+		if(tmp == UINT32_C(0x0)) {
+			insz = n + SIZE_C(0x1);
+			goto nottoobig;
+		}
+	}
+	u8c_seterr(U"u8c_u8enc: Unterminated input.",u8c_errtyp_untermin);
+	return true;
+nottoobig:;
+	if(_sz != NULL) {
+		*_sz = outsz;
+	}
+	unsigned char * out = NULL;
+	if(u8c_u8alloc(&out,outsz + SIZE_C(0x1))) {
+		return true;
+	}
+	for(register size_t n = SIZE_C(0x0), outn = SIZE_C(0x0);n < insz;n += SIZE_C(0x1),outn += SIZE_C(0x1)) { /* Second pass: encode each codepoint into UTF-8. */
+		register char32_t const tmp = _in[n];
+		if(tmp >= UINT32_C(0x10000)) { // Four bytes.
+			out[outn] =  UINT8_C(0b11110000) + (uint_least8_t)(tmp >> UINT32_C(0x12));
+			outn          += SIZE_C(0x1);
+			out[outn] =  UINT8_C(0b10000000) + (uint_least8_t)(tmp >> UINT32_C(0xC) & UINT8_C(0b00111111));
+			outn          += SIZE_C(0x1);
+			out[outn] =  UINT8_C(0b10000000) + (uint_least8_t)(tmp >> UINT32_C(0x6) & UINT8_C(0b00111111));
+			outn          += SIZE_C(0x1);
+			out[outn] =  UINT8_C(0b10000000) + (uint_least8_t)(tmp & UINT32_C(0b00111111));
+			continue;
+		}
+		if(tmp >= UINT32_C(0x800)) { /* Three bytes. */
+			out[outn] =  UINT8_C(0xE0) + (uint_least8_t)(tmp >> UINT32_C(0xC));
+			outn          += SIZE_C(0x1);
+			out[outn] =  UINT8_C(0x80) + (uint_least8_t)(tmp >> UINT32_C(0x6) & UINT8_C(0b00111111));
+			outn          += SIZE_C(0x1);
+			out[outn] =  UINT8_C(0x80) + (uint_least8_t)(tmp & UINT32_C(0b00111111));
+			continue;
+		}
+		if(tmp >= UINT32_C(0x80)) { /* Two bytes. */
+			out[outn] =  UINT8_C(0xC0) + (uint_least8_t)(tmp >> UINT8_C(0x6));
+			outn          += SIZE_C(0x1);
+			out[outn] =  UINT8_C(0x80) + (uint_least8_t)(tmp & UINT8_C(0b00111111));
+			continue;
+		}
+		/* One byte. */
+		out[outn] = (uint_least8_t)tmp;
+	}
+	u8c_u8free(_out);
+	*_out = out;
+	return false;
+}