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[ssd1306_base] Move switch tables to PROGMEM with lookup tables

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Replace three compiler-generated switch tables (CSWTCH) with PROGMEM
lookup tables, saving 84 bytes of DRAM on ESP8266.

- model_str_(): 56B string pointer table → PROGMEM_STRING_TABLE
- get_height_internal(): 14B byte table → PROGMEM struct array
- get_width_internal(): 14B byte table → PROGMEM struct array

Width and height use a single ModelDimensions struct array for
maintainability. All 14 enum values verified with static_assert.
This commit is contained in:
J. Nick Koston
2026-02-06 21:25:52 +01:00
parent eb7aa3420f
commit 8da986d41a
4 changed files with 69 additions and 84 deletions
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144
esphome/components/ssd1306_base/ssd1306_base.cpp
View File

@@ -1,6 +1,7 @@
#include "ssd1306_base.h"
#include "esphome/core/helpers.h"
#include "esphome/core/log.h"
#include "esphome/core/progmem.h"
namespace esphome {
namespace ssd1306_base {
@@ -40,6 +41,64 @@ static const uint8_t SSD1305_COMMAND_SET_AREA_COLOR = 0xD8;
static const uint8_t SH1107_COMMAND_SET_START_LINE = 0xDC;
static const uint8_t SH1107_COMMAND_CHARGE_PUMP = 0xAD;
// Verify SSD1306Model enum is sequential 0-13 so we can use it as a table index
static_assert(SSD1306_MODEL_128_32 == 0, "SSD1306Model enum values must match table indices");
static_assert(SSD1306_MODEL_128_64 == 1, "SSD1306Model enum values must match table indices");
static_assert(SSD1306_MODEL_96_16 == 2, "SSD1306Model enum values must match table indices");
static_assert(SSD1306_MODEL_64_48 == 3, "SSD1306Model enum values must match table indices");
static_assert(SSD1306_MODEL_64_32 == 4, "SSD1306Model enum values must match table indices");
static_assert(SSD1306_MODEL_72_40 == 5, "SSD1306Model enum values must match table indices");
static_assert(SH1106_MODEL_128_32 == 6, "SSD1306Model enum values must match table indices");
static_assert(SH1106_MODEL_128_64 == 7, "SSD1306Model enum values must match table indices");
static_assert(SH1106_MODEL_96_16 == 8, "SSD1306Model enum values must match table indices");
static_assert(SH1106_MODEL_64_48 == 9, "SSD1306Model enum values must match table indices");
static_assert(SH1107_MODEL_128_64 == 10, "SSD1306Model enum values must match table indices");
static_assert(SH1107_MODEL_128_128 == 11, "SSD1306Model enum values must match table indices");
static_assert(SSD1305_MODEL_128_32 == 12, "SSD1306Model enum values must match table indices");
static_assert(SSD1305_MODEL_128_64 == 13, "SSD1306Model enum values must match table indices");
// PROGMEM lookup table indexed by SSD1306Model enum (width, height per model)
struct ModelDimensions {
uint8_t width;
uint8_t height;
};
static const ModelDimensions MODEL_DIMS[] PROGMEM = {
{128, 32}, // SSD1306_MODEL_128_32
{128, 64}, // SSD1306_MODEL_128_64
{96, 16}, // SSD1306_MODEL_96_16
{64, 48}, // SSD1306_MODEL_64_48
{64, 32}, // SSD1306_MODEL_64_32
{72, 40}, // SSD1306_MODEL_72_40
{128, 32}, // SH1106_MODEL_128_32
{128, 64}, // SH1106_MODEL_128_64
{96, 16}, // SH1106_MODEL_96_16
{64, 48}, // SH1106_MODEL_64_48
{64, 128}, // SH1107_MODEL_128_64 (note: width is 64, height is 128)
{128, 128}, // SH1107_MODEL_128_128
{128, 32}, // SSD1305_MODEL_128_32
{128, 64}, // SSD1305_MODEL_128_64
};
// clang-format off
PROGMEM_STRING_TABLE(ModelStrings,
"SSD1306 128x32", // SSD1306_MODEL_128_32
"SSD1306 128x64", // SSD1306_MODEL_128_64
"SSD1306 96x16", // SSD1306_MODEL_96_16
"SSD1306 64x48", // SSD1306_MODEL_64_48
"SSD1306 64x32", // SSD1306_MODEL_64_32
"SSD1306 72x40", // SSD1306_MODEL_72_40
"SH1106 128x32", // SH1106_MODEL_128_32
"SH1106 128x64", // SH1106_MODEL_128_64
"SH1106 96x16", // SH1106_MODEL_96_16
"SH1106 64x48", // SH1106_MODEL_64_48
"SH1107 128x64", // SH1107_MODEL_128_64
"SH1107 128x128", // SH1107_MODEL_128_128
"SSD1305 128x32", // SSD1305_MODEL_128_32
"SSD1305 128x64", // SSD1305_MODEL_128_64
"Unknown" // fallback
);
// clang-format on
void SSD1306::setup() {
this->init_internal_(this->get_buffer_length_());
@@ -273,56 +332,8 @@ void SSD1306::turn_off() {
this->command(SSD1306_COMMAND_DISPLAY_OFF);
this->is_on_ = false;
}
int SSD1306::get_height_internal() {
switch (this->model_) {
case SH1107_MODEL_128_64:
case SH1107_MODEL_128_128:
return 128;
case SSD1306_MODEL_128_32:
case SSD1306_MODEL_64_32:
case SH1106_MODEL_128_32:
case SSD1305_MODEL_128_32:
return 32;
case SSD1306_MODEL_128_64:
case SH1106_MODEL_128_64:
case SSD1305_MODEL_128_64:
return 64;
case SSD1306_MODEL_96_16:
case SH1106_MODEL_96_16:
return 16;
case SSD1306_MODEL_64_48:
case SH1106_MODEL_64_48:
return 48;
case SSD1306_MODEL_72_40:
return 40;
default:
return 0;
}
}
int SSD1306::get_width_internal() {
switch (this->model_) {
case SSD1306_MODEL_128_32:
case SH1106_MODEL_128_32:
case SSD1306_MODEL_128_64:
case SH1106_MODEL_128_64:
case SSD1305_MODEL_128_32:
case SSD1305_MODEL_128_64:
case SH1107_MODEL_128_128:
return 128;
case SSD1306_MODEL_96_16:
case SH1106_MODEL_96_16:
return 96;
case SSD1306_MODEL_64_48:
case SSD1306_MODEL_64_32:
case SH1106_MODEL_64_48:
case SH1107_MODEL_128_64:
return 64;
case SSD1306_MODEL_72_40:
return 72;
default:
return 0;
}
}
int SSD1306::get_height_internal() { return progmem_read_byte(&MODEL_DIMS[this->model_].height); }
int SSD1306::get_width_internal() { return progmem_read_byte(&MODEL_DIMS[this->model_].width); }
size_t SSD1306::get_buffer_length_() {
return size_t(this->get_width_internal()) * size_t(this->get_height_internal()) / 8u;
}
@@ -361,37 +372,8 @@ void SSD1306::init_reset_() {
this->reset_pin_->digital_write(true);
}
}
const char *SSD1306::model_str_() {
switch (this->model_) {
case SSD1306_MODEL_128_32:
return "SSD1306 128x32";
case SSD1306_MODEL_128_64:
return "SSD1306 128x64";
case SSD1306_MODEL_64_32:
return "SSD1306 64x32";
case SSD1306_MODEL_96_16:
return "SSD1306 96x16";
case SSD1306_MODEL_64_48:
return "SSD1306 64x48";
case SSD1306_MODEL_72_40:
return "SSD1306 72x40";
case SH1106_MODEL_128_32:
return "SH1106 128x32";
case SH1106_MODEL_128_64:
return "SH1106 128x64";
case SH1106_MODEL_96_16:
return "SH1106 96x16";
case SH1106_MODEL_64_48:
return "SH1106 64x48";
case SH1107_MODEL_128_64:
return "SH1107 128x64";
case SSD1305_MODEL_128_32:
return "SSD1305 128x32";
case SSD1305_MODEL_128_64:
return "SSD1305 128x64";
default:
return "Unknown";
}
const LogString *SSD1306::model_str_() {
return ModelStrings::get_log_str(static_cast<uint8_t>(this->model_), ModelStrings::LAST_INDEX);
}
} // namespace ssd1306_base

5
esphome/components/ssd1306_base/ssd1306_base.h
View File

@@ -5,6 +5,9 @@
#include "esphome/components/display/display_buffer.h"
namespace esphome {
struct LogString;
namespace ssd1306_base {
enum SSD1306Model {
@@ -70,7 +73,7 @@ class SSD1306 : public display::DisplayBuffer {
int get_height_internal() override;
int get_width_internal() override;
size_t get_buffer_length_();
const char *model_str_();
const LogString *model_str_();
SSD1306Model model_{SSD1306_MODEL_128_64};
GPIOPin *reset_pin_{nullptr};

2
esphome/components/ssd1306_i2c/ssd1306_i2c.cpp
View File

@@ -28,7 +28,7 @@ void I2CSSD1306::dump_config() {
" Offset X: %d\n"
" Offset Y: %d\n"
" Inverted Color: %s",
this->model_str_(), YESNO(this->external_vcc_), YESNO(this->flip_x_), YESNO(this->flip_y_),
LOG_STR_ARG(this->model_str_()), YESNO(this->external_vcc_), YESNO(this->flip_x_), YESNO(this->flip_y_),
this->offset_x_, this->offset_y_, YESNO(this->invert_));
LOG_I2C_DEVICE(this);
LOG_PIN(" Reset Pin: ", this->reset_pin_);

2
esphome/components/ssd1306_spi/ssd1306_spi.cpp
View File

@@ -24,7 +24,7 @@ void SPISSD1306::dump_config() {
" Offset X: %d\n"
" Offset Y: %d\n"
" Inverted Color: %s",
this->model_str_(), YESNO(this->external_vcc_), YESNO(this->flip_x_), YESNO(this->flip_y_),
LOG_STR_ARG(this->model_str_()), YESNO(this->external_vcc_), YESNO(this->flip_x_), YESNO(this->flip_y_),
this->offset_x_, this->offset_y_, YESNO(this->invert_));
LOG_PIN(" CS Pin: ", this->cs_);
LOG_PIN(" DC Pin: ", this->dc_pin_);