From 97b13672ced335dd7a8c4c926a150ddffb63d401 Mon Sep 17 00:00:00 2001
From: "Sven M. Hallberg" <pesco@khjk.org>
Date: Fri, 11 Jan 2013 00:41:34 +0100
Subject: [PATCH] generalize act_base64_n
---
examples/base64_sem1.c | 73 ++++++++++++++++--------------------------
1 file changed, 27 insertions(+), 46 deletions(-)
diff --git a/examples/base64_sem1.c b/examples/base64_sem1.c
index 7839435a..6dbb2fd3 100644
--- a/examples/base64_sem1.c
+++ b/examples/base64_sem1.c
@@ -78,70 +78,51 @@ const HParsedToken *act_bsfdig(const HParseResult *p)
#define act_document act_index0
-// helper
-void carray_append_uint(HCountedArray *array, uint8_t value)
-{
- HParsedToken *item = h_arena_malloc(array->arena, sizeof(HParsedToken));
- item->token_type = TT_UINT;
- item->uint = value;
- h_carray_append(array, item);
-}
-
-const HParsedToken *act_base64_3(const HParseResult *p)
+// General-form action to turn a block of base64 digits into bytes.
+const HParsedToken *act_base64_n(int n, const HParseResult *p)
{
assert(p->ast->token_type == TT_SEQUENCE);
HParsedToken *res = h_arena_malloc(p->arena, sizeof(HParsedToken));
res->token_type = TT_SEQUENCE;
- res->seq = h_carray_new_sized(p->arena, 4);
+ res->seq = h_carray_new_sized(p->arena, n);
HParsedToken **digits = p->ast->seq->elements;
- uint32_t x = digits[0]->uint;
- x <<= 6; x |= digits[1]->uint;
- x <<= 6; x |= digits[2]->uint;
- x <<= 6; x |= digits[3]->uint;
- carray_append_uint(res->seq, (x >> 16) & 0xFF);
- carray_append_uint(res->seq, (x >> 8) & 0xFF);
- carray_append_uint(res->seq, x & 0xFF);
+ uint32_t x = 0;
+ int bits = 0;
+ for(int i=0; i<n+1; i++) {
+ x <<= 6; x |= digits[i]->uint;
+ bits += 6;
+ }
+ x >>= bits%8; // align, i.e. cut off extra bits
+
+ for(int i=0; i<n; i++) {
+ HParsedToken *item = h_arena_malloc(p->arena, sizeof(HParsedToken));
+ item->token_type = TT_UINT;
+ item->uint = x & 0xFF;
+
+ res->seq->elements[n-1-i] = item; // output the last byte and
+ x >>= 8; // discard it
+ }
+ res->seq->used = n;
return res;
}
-const HParsedToken *act_base64_2(const HParseResult *p)
+const HParsedToken *act_base64_3(const HParseResult *p)
{
- assert(p->ast->token_type == TT_SEQUENCE);
-
- HParsedToken *res = h_arena_malloc(p->arena, sizeof(HParsedToken));
- res->token_type = TT_SEQUENCE;
- res->seq = h_carray_new_sized(p->arena, 4);
-
- HParsedToken **digits = p->ast->seq->elements;
- uint32_t x = digits[0]->uint;
- x <<= 6; x |= digits[1]->uint;
- x <<= 6; x |= digits[2]->uint;
-
- carray_append_uint(res->seq, (x >> 10) & 0xFF);
- carray_append_uint(res->seq, (x >> 2) & 0xFF);
+ return act_base64_n(3, p);
+}
- return res;
+const HParsedToken *act_base64_2(const HParseResult *p)
+{
+ return act_base64_n(2, p);
}
const HParsedToken *act_base64_1(const HParseResult *p)
{
- assert(p->ast->token_type == TT_SEQUENCE);
-
- HParsedToken *res = h_arena_malloc(p->arena, sizeof(HParsedToken));
- res->token_type = TT_SEQUENCE;
- res->seq = h_carray_new_sized(p->arena, 4);
-
- HParsedToken **digits = p->ast->seq->elements;
- uint32_t x = digits[0]->uint;
- x <<= 6; x |= digits[1]->uint;
-
- carray_append_uint(res->seq, (x >> 4) & 0xFF);
-
- return res;
+ return act_base64_n(1, p);
}
#if 0
--
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