From a2a1e4bbfcda8c1314b592c8c940e96e95cb68d4 Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Wed, 3 Aug 2022 00:23:50 +0200
Subject: shared: clean up printf, %u support (amongst other things)
---
src/shared/printf.c | 172 +++++++++++++++++++++++++++++++++++-----------------
1 file changed, 117 insertions(+), 55 deletions(-)
(limited to 'src/shared/printf.c')
diff --git a/src/shared/printf.c b/src/shared/printf.c
index b50d4ef..47d56f8 100644
--- a/src/shared/printf.c
+++ b/src/shared/printf.c
@@ -1,71 +1,133 @@
+#include <stdbool.h>
#include <shared/mem.h>
#include <shared/printf.h>
+struct out_state {
+ void (*back)(void *, const char *, size_t);
+ void *backarg;
+ int written;
+};
+
+static int output(struct out_state *os, const char *buf, size_t len) {
+ if (len) os->back(os->backarg, buf, len);
+ os->written += len;
+ return os->written;
+}
+
+static void output_c(struct out_state *os, char c) {
+ output(os, &c, 1);
+}
+
+
+struct mods {
+ char fill_char;
+ size_t field_width;
+};
+
+static void pad(struct out_state *os, struct mods *m, size_t len) {
+ for (size_t i = 0; len + i < m->field_width; i++)
+ output(os, &m->fill_char, 1);
+}
+
+static void output_uint(struct out_state *os, struct mods *m, unsigned long long n) {
+ // TODO static assert sizeof(unsigned long long) <= 8
+ char buf[20];
+ size_t pos = sizeof(buf);
+
+ if (!n) {
+ buf[--pos] = '0';
+ } else while (n) {
+ unsigned long long q = n / 10, r = n % 10;
+ buf[--pos] = r + '0';
+ n = q;
+ }
+ pad(os, m, sizeof(buf) - pos);
+ output(os, buf + pos, sizeof(buf) - pos);
+}
+
+
int __printf_internal(const char *fmt, va_list argp,
- void (*back)(void*, const char*, size_t), void *back_arg)
+ void (*back)(void*, const char*, size_t), void *backarg)
{
- const char *seg = fmt; // beginning of the current segment
- int total = 0;
+ const char *seg = fmt; /* beginning of the current non-modifier streak */
+ struct out_state os = {
+ .back = back,
+ .backarg = backarg,
+ };
for (;;) {
char c = *fmt++;
+ if (c == '\0') {
+ return output(&os, seg, fmt - seg - 1);
+ }
+ if (c != '%') continue;
+ output(&os, seg, fmt - seg - 1);
+
+ struct mods m = {
+ .fill_char = ' ',
+ .field_width = 0,
+ };
+
+ for (bool modifier = true; modifier;) {
+ c = *fmt++;
+ switch (c) {
+ case '0':
+ m.fill_char = '0';
+ break;
+ default:
+ modifier = false;
+ break;
+ }
+ }
+
+ while ('0' <= c && c <= '9') {
+ m.field_width *= 10;
+ m.field_width += c - '0';
+ c = *fmt++;
+ }
+
+ // TODO length modifiers
+
switch (c) {
- case '\0':
- back(back_arg, seg, fmt - seg - 1);
- return total + (fmt - seg - 1);
+ unsigned long n, len;
- case '%':
- back(back_arg, seg, fmt - seg - 1);
- total += fmt - seg - 1;
- size_t pad_len = 0;
-
- c = *fmt++;
- while (1) {
- switch (c) {
- case '0':
- pad_len = *fmt++ - '0'; // can skip over the null byte, idc
- break;
- default:
- goto modifier_break;
- }
- c = *fmt++;
+ case 'c':
+ output_c(&os, va_arg(argp, int));
+ break;
+
+ case 's':
+ const char *s = va_arg(argp, char*);
+ if (s) {
+ len = strlen(s);
+ pad(&os, &m, len);
+ output(&os, s, len);
+ } else {
+ pad(&os, &m, 0);
}
-modifier_break:
- switch (c) {
- case 'c':
- char c = va_arg(argp, int);
- back(back_arg, &c, 1);
- total += 1;
- break;
-
- case 's':
- const char *s = va_arg(argp, char*);
- if (s) {
- back(back_arg, s, strlen(s));
- total += strlen(s);
- }
- break;
-
- case 'x':
- unsigned long n = va_arg(argp, long);
- size_t i = 4; // nibbles * 4
- while (n >> i && i < (sizeof(n) * 8))
- i += 4;
-
- if (i < pad_len * 4)
- i = pad_len * 4;
-
- while (i > 0) {
- i -= 4;
- char h = '0' + ((n >> i) & 0xf);
- if (h > '9') h += 'a' - '9' - 1;
- back(back_arg, &h, 1);
- total++;
- }
- break;
+ break;
+
+ case 'x':
+ n = va_arg(argp, unsigned long);
+ len = 1;
+ while (n >> (len * 4) && (len * 4) < (sizeof(n) * 8))
+ len++;
+ pad(&os, &m, len);
+ while (len-- > 0) {
+ char h = '0' + ((n >> (len * 4)) & 0xf);
+ if (h > '9') h += 'a' - '9' - 1;
+ output_c(&os, h);
}
- seg = fmt;
+ break;
+
+ case 'u':
+ n = va_arg(argp, unsigned long);
+ output_uint(&os, &m, n);
+ break;
+
+ case '%':
+ output(&os, "%", 1);
break;
}
+ seg = fmt;
}
}
--
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