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commit e957e1633c1b036b1251dfdf7ebc3460db20de9d Author: Huang Qi <[email protected]> AuthorDate: Thu Mar 2 17:38:46 2023 +0800 nsh: Improve performance of `help` by line buffer This change reduce the usage of `printf`, which will improve both CPU usage and IO performance. Signed-off-by: Huang Qi <[email protected]> --- nshlib/nsh_command.c | 37 ++++++++++++++++++++++++++++--------- 1 file changed, 28 insertions(+), 9 deletions(-) diff --git a/nshlib/nsh_command.c b/nshlib/nsh_command.c index f3a7af0f5..6352890ba 100644 --- a/nshlib/nsh_command.c +++ b/nshlib/nsh_command.c @@ -615,6 +615,8 @@ static inline void help_cmdlist(FAR struct nsh_vtbl_s *vtbl) unsigned int i; unsigned int j; unsigned int k; + unsigned int offset; + char line[HELP_LINELEN]; /* Pick an optimal column width */ @@ -650,22 +652,32 @@ static inline void help_cmdlist(FAR struct nsh_vtbl_s *vtbl) for (i = 0; i < ncmdrows; i++) { - nsh_output(vtbl, " "); + /* Tab before a new line */ + + offset = 4; + memset(line, ' ', offset); + for (j = 0, k = i; j < cmdsperline && k < NUM_CMDS; j++, k += ncmdrows) { - nsh_output(vtbl, "%s", g_cmdmap[k].cmd); + /* Copy the cmd name to line buffer */ + + offset += strlcpy(line + offset, g_cmdmap[k].cmd, + sizeof(line) - offset); + + /* Add space between commands */ for (cmdwidth = strlen(g_cmdmap[k].cmd); cmdwidth < colwidth; cmdwidth++) { - nsh_output(vtbl, " "); + line[offset++] = ' '; } } - nsh_output(vtbl, "\n"); + line[offset++] = '\n'; + nsh_write(vtbl, line, offset); } } #endif @@ -796,6 +808,9 @@ static inline void help_builtins(FAR struct nsh_vtbl_s *vtbl) unsigned int i; unsigned int j; unsigned int k; + unsigned int offset; + char line[HELP_LINELEN]; + static const char *g_builtin_prompt = "\nBuiltin Apps:\n"; /* Count the number of built-in commands and get the optimal column width */ @@ -845,10 +860,12 @@ static inline void help_builtins(FAR struct nsh_vtbl_s *vtbl) /* List the set of available built-in commands */ - nsh_output(vtbl, "\nBuiltin Apps:\n"); + nsh_write(vtbl, g_builtin_prompt, strlen(g_builtin_prompt)); for (i = 0; i < num_builtin_rows; i++) { - nsh_output(vtbl, " "); + offset = 4; + memset(line, ' ', offset); + for (j = 0, k = i; j < builtins_per_line && (builtin = builtin_for_index(k)); @@ -859,17 +876,19 @@ static inline void help_builtins(FAR struct nsh_vtbl_s *vtbl) continue; } - nsh_output(vtbl, "%s", builtin->name); + offset += strlcpy(line + offset, builtin->name, + sizeof(line) - offset); for (builtin_width = strlen(builtin->name); builtin_width < column_width; builtin_width++) { - nsh_output(vtbl, " "); + line[offset++] = ' '; } } - nsh_output(vtbl, "\n"); + line[offset++] = '\n'; + nsh_write(vtbl, line, offset); } #endif }
